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class="toctree-l1"><a class="reference internal" href="network-simulator.html">Network Simulator</a></li> <li class="toctree-l1"><a class="reference internal" href="clauses.html">Clauses</a></li> <li class="toctree-l1"><a class="reference internal" href="merkle-trees.html">Transaction tear-offs</a></li> </ul> <p class="caption"><span class="caption-text">Component library</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="contract-catalogue.html">Contract catalogue</a></li> <li class="toctree-l1"><a class="reference internal" href="contract-irs.html">Interest rate swaps</a></li> </ul> <p class="caption"><span class="caption-text">Appendix</span></p> <ul> <li class="toctree-l1"><a class="reference internal" href="loadtesting.html">Load testing</a></li> <li class="toctree-l1"><a class="reference internal" href="setting-up-a-corda-network.html">What is a corda network?</a></li> <li class="toctree-l1"><a class="reference internal" 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href="glossary.html">Glossary</a></li> </ul> </div> </div> </nav> <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"> <nav class="wy-nav-top" role="navigation" aria-label="top navigation"> <i data-toggle="wy-nav-top" class="fa fa-bars"></i> <a href="index.html">R3 Corda</a> </nav> <div class="wy-nav-content"> <div class="rst-content"> <div role="navigation" aria-label="breadcrumbs navigation"> <ul class="wy-breadcrumbs"> <li><a href="index.html">Docs</a> »</li> <li>Writing a contract test</li> <li class="wy-breadcrumbs-aside"> <a href="_sources/tutorial-test-dsl.txt" rel="nofollow"> View page source</a> </li> </ul> <hr/> </div> <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article"> <div itemprop="articleBody"> <script type="text/javascript" src="_static/jquery.js"></script> <script type="text/javascript" src="_static/codesets.js"></script><div class="section" id="writing-a-contract-test"> <h1>Writing a contract test<a class="headerlink" href="#writing-a-contract-test" title="Permalink to this headline">¶</a></h1> <p>This tutorial will take you through the steps required to write a contract test using Kotlin and Java.</p> <p>The testing DSL allows one to define a piece of the ledger with transactions referring to each other, and ways of verifying their correctness.</p> <div class="section" id="testing-single-transactions"> <h2>Testing single transactions<a class="headerlink" href="#testing-single-transactions" title="Permalink to this headline">¶</a></h2> <p>We start with the empty ledger:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">CommercialPaperTest</span><span class="p">{</span> <span class="n">@Test</span> <span class="k">fun</span> <span class="nf">emptyLedger</span><span class="p">()</span> <span class="p">{</span> <span class="n">ledger</span> <span class="p">{</span> <span class="p">}</span> <span class="p">}</span> <span class="p">...</span> <span class="p">}</span> </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">static</span> <span class="n">net</span><span class="o">.</span><span class="na">corda</span><span class="o">.</span><span class="na">core</span><span class="o">.</span><span class="na">testing</span><span class="o">.</span><span class="na">JavaTestHelpers</span><span class="o">.*;</span> <span class="kn">import</span> <span class="nn">static</span> <span class="n">net</span><span class="o">.</span><span class="na">corda</span><span class="o">.</span><span class="na">core</span><span class="o">.</span><span class="na">contracts</span><span class="o">.</span><span class="na">JavaTestHelpers</span><span class="o">.*;</span> <span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">emptyLedger</span><span class="o">()</span> <span class="o">{</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="c1">// We need to return this explicitly</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>The DSL keyword <code class="docutils literal"><span class="pre">ledger</span></code> takes a closure that can build up several transactions and may verify their overall correctness. A ledger is effectively a fresh world with no pre-existing transactions or services within it.</p> <p>We will start with defining helper function that returns a <code class="docutils literal"><span class="pre">CommercialPaper</span></code> state:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>fun getPaper(): ICommercialPaperState = CommercialPaper.State( issuance = MEGA_CORP.ref(123), owner = MEGA_CORP_PUBKEY, faceValue = 1000.DOLLARS `issued by` MEGA_CORP.ref(123), maturityDate = TEST_TX_TIME + 7.days ) </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="kd">private</span> <span class="kd">final</span> <span class="n">OpaqueBytes</span> <span class="n">defaultRef</span> <span class="o">=</span> <span class="k">new</span> <span class="n">OpaqueBytes</span><span class="o">(</span><span class="k">new</span> <span class="kt">byte</span><span class="o">[]{</span><span class="mi">123</span><span class="o">});</span> <span class="kd">private</span> <span class="n">ICommercialPaperState</span> <span class="nf">getPaper</span><span class="o">()</span> <span class="o">{</span> <span class="k">return</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span><span class="o">(</span> <span class="n">getMEGA_CORP</span><span class="o">().</span><span class="na">ref</span><span class="o">(</span><span class="n">defaultRef</span><span class="o">),</span> <span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">1000</span><span class="o">),</span> <span class="n">getMEGA_CORP</span><span class="o">().</span><span class="na">ref</span><span class="o">(</span><span class="n">defaultRef</span><span class="o">)),</span> <span class="n">getTEST_TX_TIME</span><span class="o">().</span><span class="na">plus</span><span class="o">(</span><span class="mi">7</span><span class="o">,</span> <span class="n">ChronoUnit</span><span class="o">.</span><span class="na">DAYS</span><span class="o">)</span> <span class="o">);</span> <span class="o">}</span> </pre></div> </div> </div> <p>It’s a <code class="docutils literal"><span class="pre">CommercialPaper</span></code> issued by <code class="docutils literal"><span class="pre">MEGA_CORP</span></code> with face value of $1000 and maturity date in 7 days.</p> <p>Let’s add a <code class="docutils literal"><span class="pre">CommercialPaper</span></code> transaction:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">@Test</span> <span class="k">fun</span> <span class="nf">simpleCPDoesntCompile</span><span class="p">()</span> <span class="p">{</span> <span class="k">val</span> <span class="py">inState</span> <span class="p">=</span> <span class="n">getPaper</span><span class="p">()</span> <span class="n">ledger</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">{</span> <span class="n">input</span><span class="p">(</span><span class="n">inState</span><span class="p">)</span> <span class="p">}</span> <span class="p">}</span> <span class="p">}</span> </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCPDoesntCompile</span><span class="o">()</span> <span class="o">{</span> <span class="n">ICommercialPaperState</span> <span class="n">inState</span> <span class="o">=</span> <span class="n">getPaper</span><span class="o">();</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="n">inState</span><span class="o">);</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>We can add a transaction to the ledger using the <code class="docutils literal"><span class="pre">transaction</span></code> primitive. The transaction in turn may be defined by specifying <code class="docutils literal"><span class="pre">input</span></code>-s, <code class="docutils literal"><span class="pre">output</span></code>-s, <code class="docutils literal"><span class="pre">command</span></code>-s and <code class="docutils literal"><span class="pre">attachment</span></code>-s.</p> <p>The above <code class="docutils literal"><span class="pre">input</span></code> call is a bit special; transactions don’t actually contain input states, just references to output states of other transactions. Under the hood the above <code class="docutils literal"><span class="pre">input</span></code> call creates a dummy transaction in the ledger (that won’t be verified) which outputs the specified state, and references that from this transaction.</p> <p>The above code however doesn’t compile:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">Error</span><span class="p">:(</span><span class="m">29</span><span class="p">,</span> <span class="m">17</span><span class="p">)</span> <span class="n">Kotlin</span><span class="p">:</span> <span class="n">Type</span> <span class="n">mismatch</span><span class="p">:</span> <span class="n">inferred</span> <span class="n">type</span> <span class="k">is</span> <span class="n">Unit</span> <span class="n">but</span> <span class="n">EnforceVerifyOrFail</span> <span class="n">was</span> <span class="n">expected</span> </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nl">Error:</span><span class="o">(</span><span class="mi">35</span><span class="o">,</span> <span class="mi">27</span><span class="o">)</span> <span class="n">java</span><span class="o">:</span> <span class="n">incompatible</span> <span class="n">types</span><span class="o">:</span> <span class="n">bad</span> <span class="k">return</span> <span class="n">type</span> <span class="n">in</span> <span class="n">lambda</span> <span class="n">expression</span> <span class="n">missing</span> <span class="k">return</span> <span class="n">value</span> </pre></div> </div> </div> <p>This is deliberate: The DSL forces us to specify either <code class="docutils literal"><span class="pre">this.verifies()</span></code> or <code class="docutils literal"><span class="pre">this</span> <span class="pre">`fails</span> <span class="pre">with`</span> <span class="pre">"some</span> <span class="pre">text"</span></code> on the last line of <code class="docutils literal"><span class="pre">transaction</span></code>:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">@Test</span> <span class="k">fun</span> <span class="nf">simpleCP</span><span class="p">()</span> <span class="p">{</span> <span class="k">val</span> <span class="py">inState</span> <span class="p">=</span> <span class="n">getPaper</span><span class="p">()</span> <span class="n">ledger</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">{</span> <span class="n">input</span><span class="p">(</span><span class="n">inState</span><span class="p">)</span> <span class="k">this</span><span class="p">.</span><span class="n">verifies</span><span class="p">()</span> <span class="p">}</span> <span class="p">}</span> <span class="p">}</span> </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCP</span><span class="o">()</span> <span class="o">{</span> <span class="n">ICommercialPaperState</span> <span class="n">inState</span> <span class="o">=</span> <span class="n">getPaper</span><span class="o">();</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="n">inState</span><span class="o">);</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>Let’s take a look at a transaction that fails.</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">@Test</span> <span class="k">fun</span> <span class="nf">simpleCPMove</span><span class="p">()</span> <span class="p">{</span> <span class="k">val</span> <span class="py">inState</span> <span class="p">=</span> <span class="n">getPaper</span><span class="p">()</span> <span class="n">ledger</span> <span class="p">{</span> <span class="n">transaction</span> <span class="p">{</span> <span class="n">input</span><span class="p">(</span><span class="n">inState</span><span class="p">)</span> <span class="n">command</span><span class="p">(</span><span class="n">MEGA_CORP_PUBKEY</span><span class="p">)</span> <span class="p">{</span> <span class="n">CommercialPaper</span><span class="p">.</span><span class="n">Commands</span><span class="p">.</span><span class="n">Move</span><span class="p">()</span> <span class="p">}</span> <span class="k">this</span><span class="p">.</span><span class="n">verifies</span><span class="p">()</span> <span class="p">}</span> <span class="p">}</span> <span class="p">}</span> </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCPMove</span><span class="o">()</span> <span class="o">{</span> <span class="n">ICommercialPaperState</span> <span class="n">inState</span> <span class="o">=</span> <span class="n">getPaper</span><span class="o">();</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="n">inState</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>When run, that code produces the following error:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>net.corda.core.contracts.TransactionVerificationException$ContractRejection: java.lang.IllegalArgumentException: Failed requirement: the state is propagated </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="n">net</span><span class="o">.</span><span class="na">corda</span><span class="o">.</span><span class="na">core</span><span class="o">.</span><span class="na">contracts</span><span class="o">.</span><span class="na">TransactionVerificationException$ContractRejection</span><span class="o">:</span> <span class="n">java</span><span class="o">.</span><span class="na">lang</span><span class="o">.</span><span class="na">IllegalStateException</span><span class="o">:</span> <span class="n">the</span> <span class="n">state</span> <span class="n">is</span> <span class="n">propagated</span> </pre></div> </div> </div> <p>The transaction verification failed, because we wanted to move paper but didn’t specify an output - but the state should be propagated. However we can specify that this is an intended behaviour by changing <code class="docutils literal"><span class="pre">this.verifies()</span></code> to <code class="docutils literal"><span class="pre">this</span> <span class="pre">`fails</span> <span class="pre">with`</span> <span class="pre">"the</span> <span class="pre">state</span> <span class="pre">is</span> <span class="pre">propagated"</span></code>:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun simpleCPMoveFails() { val inState = getPaper() ledger { transaction { input(inState) command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this `fails with` "the state is propagated" } } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCPMoveFails</span><span class="o">()</span> <span class="o">{</span> <span class="n">ICommercialPaperState</span> <span class="n">inState</span> <span class="o">=</span> <span class="n">getPaper</span><span class="o">();</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="n">inState</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">failsWith</span><span class="o">(</span><span class="s">"the state is propagated"</span><span class="o">);</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>We can continue to build the transaction until it <code class="docutils literal"><span class="pre">verifies</span></code>:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun simpleCPMoveSuccess() { val inState = getPaper() ledger { transaction { input(inState) command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this `fails with` "the state is propagated" output("alice's paper") { inState `owned by` ALICE_PUBKEY } this.verifies() } } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCPMoveSuccess</span><span class="o">()</span> <span class="o">{</span> <span class="n">ICommercialPaperState</span> <span class="n">inState</span> <span class="o">=</span> <span class="n">getPaper</span><span class="o">();</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="n">inState</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">failsWith</span><span class="o">(</span><span class="s">"the state is propagated"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's paper"</span><span class="o">,</span> <span class="n">inState</span><span class="o">.</span><span class="na">withOwner</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">()));</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p><code class="docutils literal"><span class="pre">output</span></code> specifies that we want the input state to be transferred to <code class="docutils literal"><span class="pre">ALICE</span></code> and <code class="docutils literal"><span class="pre">command</span></code> adds the <code class="docutils literal"><span class="pre">Move</span></code> command itself, signed by the current owner of the input state, <code class="docutils literal"><span class="pre">MEGA_CORP_PUBKEY</span></code>.</p> <p>We constructed a complete signed commercial paper transaction and verified it. Note how we left in the <code class="docutils literal"><span class="pre">fails</span> <span class="pre">with</span></code> line - this is fine, the failure will be tested on the partially constructed transaction.</p> <p>What should we do if we wanted to test what happens when the wrong party signs the transaction? If we simply add a <code class="docutils literal"><span class="pre">command</span></code> it will permanently ruin the transaction... Enter <code class="docutils literal"><span class="pre">tweak</span></code>:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun `simple issuance with tweak`() { ledger { transaction { output("paper") { getPaper() } // Some CP is issued onto the ledger by MegaCorp. tweak { command(DUMMY_PUBKEY_1) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this `fails with` "output states are issued by a command signer" } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this.verifies() } } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleIssuanceWithTweak</span><span class="o">()</span> <span class="o">{</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"paper"</span><span class="o">,</span> <span class="n">getPaper</span><span class="o">());</span> <span class="c1">// Some CP is issued onto the ledger by MegaCorp.</span> <span class="n">tx</span><span class="o">.</span><span class="na">tweak</span><span class="o">(</span><span class="n">tw</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tw</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getDUMMY_PUBKEY_1</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tw</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tw</span><span class="o">.</span><span class="na">failsWith</span><span class="o">(</span><span class="s">"output states are issued by a command signer"</span><span class="o">);</span> <span class="o">});</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p><code class="docutils literal"><span class="pre">tweak</span></code> creates a local copy of the transaction. This makes possible to locally “ruin” the transaction while not modifying the original one, allowing testing of different error conditions.</p> <p>We now have a neat little test that tests a single transaction. This is already useful, and in fact testing of a single transaction in this way is very common. There is even a shorthand top-level <code class="docutils literal"><span class="pre">transaction</span></code> primitive that creates a ledger with a single transaction:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun `simple issuance with tweak and top level transaction`() { transaction { output("paper") { getPaper() } // Some CP is issued onto the ledger by MegaCorp. tweak { command(DUMMY_PUBKEY_1) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this `fails with` "output states are issued by a command signer" } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this.verifies() } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleIssuanceWithTweakTopLevelTx</span><span class="o">()</span> <span class="o">{</span> <span class="n">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"paper"</span><span class="o">,</span> <span class="n">getPaper</span><span class="o">());</span> <span class="c1">// Some CP is issued onto the ledger by MegaCorp.</span> <span class="n">tx</span><span class="o">.</span><span class="na">tweak</span><span class="o">(</span><span class="n">tw</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tw</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getDUMMY_PUBKEY_1</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tw</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tw</span><span class="o">.</span><span class="na">failsWith</span><span class="o">(</span><span class="s">"output states are issued by a command signer"</span><span class="o">);</span> <span class="o">});</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> </div> <div class="section" id="chaining-transactions"> <h2>Chaining transactions<a class="headerlink" href="#chaining-transactions" title="Permalink to this headline">¶</a></h2> <p>Now that we know how to define a single transaction, let’s look at how to define a chain of them:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun `chain commercial paper`() { val issuer = MEGA_CORP.ref(123) ledger { unverifiedTransaction { output("alice's $900", 900.DOLLARS.CASH `issued by` issuer `owned by` ALICE_PUBKEY) } // Some CP is issued onto the ledger by MegaCorp. transaction("Issuance") { output("paper") { getPaper() } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this.verifies() } transaction("Trade") { input("paper") input("alice's $900") output("borrowed $900") { 900.DOLLARS.CASH `issued by` issuer `owned by` MEGA_CORP_PUBKEY } output("alice's paper") { "paper".output<ICommercialPaperState>() `owned by` ALICE_PUBKEY } command(ALICE_PUBKEY) { Cash.Commands.Move() } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this.verifies() } } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">chainCommercialPaper</span><span class="o">()</span> <span class="o">{</span> <span class="n">PartyAndReference</span> <span class="n">issuer</span> <span class="o">=</span> <span class="n">getMEGA_CORP</span><span class="o">().</span><span class="na">ref</span><span class="o">(</span><span class="n">defaultRef</span><span class="o">);</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">unverifiedTransaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's $900"</span><span class="o">,</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">State</span><span class="o">(</span><span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">900</span><span class="o">),</span> <span class="n">issuer</span><span class="o">),</span> <span class="n">getALICE_PUBKEY</span><span class="o">(),</span> <span class="kc">null</span><span class="o">));</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="c1">// Some CP is issued onto the ledger by MegaCorp.</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="s">"Issuance"</span><span class="o">,</span> <span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"paper"</span><span class="o">,</span> <span class="n">getPaper</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="s">"Trade"</span><span class="o">,</span> <span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"paper"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"alice's $900"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"borrowed $900"</span><span class="o">,</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">State</span><span class="o">(</span><span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">900</span><span class="o">),</span> <span class="n">issuer</span><span class="o">),</span> <span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="kc">null</span><span class="o">));</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span> <span class="n">inputPaper</span> <span class="o">=</span> <span class="n">l</span><span class="o">.</span><span class="na">retrieveOutput</span><span class="o">(</span><span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="s">"paper"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's paper"</span><span class="o">,</span> <span class="n">inputPaper</span><span class="o">.</span><span class="na">withOwner</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">()));</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>In this example we declare that <code class="docutils literal"><span class="pre">ALICE</span></code> has $900 but we don’t care where from. For this we can use <code class="docutils literal"><span class="pre">unverifiedTransaction</span></code>. Note how we don’t need to specify <code class="docutils literal"><span class="pre">this.verifies()</span></code>.</p> <p>Notice that we labelled output with <code class="docutils literal"><span class="pre">"alice's</span> <span class="pre">$900"</span></code>, also in transaction named <code class="docutils literal"><span class="pre">"Issuance"</span></code> we labelled a commercial paper with <code class="docutils literal"><span class="pre">"paper"</span></code>. Now we can subsequently refer to them in other transactions, e.g. by <code class="docutils literal"><span class="pre">input("alice's</span> <span class="pre">$900")</span></code> or <code class="docutils literal"><span class="pre">"paper".output<ICommercialPaperState>()</span></code>.</p> <p>The last transaction named <code class="docutils literal"><span class="pre">"Trade"</span></code> exemplifies simple fact of selling the <code class="docutils literal"><span class="pre">CommercialPaper</span></code> to Alice for her $900, $100 less than the face value at 10% interest after only 7 days.</p> <p>We can also test whole ledger calling <code class="docutils literal"><span class="pre">this.verifies()</span></code> and <code class="docutils literal"><span class="pre">this.fails()</span></code> on the ledger level. To do so let’s create a simple example that uses the same input twice:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun `chain commercial paper double spend`() { val issuer = MEGA_CORP.ref(123) ledger { unverifiedTransaction { output("alice's $900", 900.DOLLARS.CASH `issued by` issuer `owned by` ALICE_PUBKEY) } // Some CP is issued onto the ledger by MegaCorp. transaction("Issuance") { output("paper") { getPaper() } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this.verifies() } transaction("Trade") { input("paper") input("alice's $900") output("borrowed $900") { 900.DOLLARS.CASH `issued by` issuer `owned by` MEGA_CORP_PUBKEY } output("alice's paper") { "paper".output<ICommercialPaperState>() `owned by` ALICE_PUBKEY } command(ALICE_PUBKEY) { Cash.Commands.Move() } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this.verifies() } transaction { input("paper") // We moved a paper to another pubkey. output("bob's paper") { "paper".output<ICommercialPaperState>() `owned by` BOB_PUBKEY } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this.verifies() } this.fails() } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">chainCommercialPaperDoubleSpend</span><span class="o">()</span> <span class="o">{</span> <span class="n">PartyAndReference</span> <span class="n">issuer</span> <span class="o">=</span> <span class="n">getMEGA_CORP</span><span class="o">().</span><span class="na">ref</span><span class="o">(</span><span class="n">defaultRef</span><span class="o">);</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">unverifiedTransaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's $900"</span><span class="o">,</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">State</span><span class="o">(</span><span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">900</span><span class="o">),</span> <span class="n">issuer</span><span class="o">),</span> <span class="n">getALICE_PUBKEY</span><span class="o">(),</span> <span class="kc">null</span><span class="o">));</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="c1">// Some CP is issued onto the ledger by MegaCorp.</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="s">"Issuance"</span><span class="o">,</span> <span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"paper"</span><span class="o">,</span> <span class="n">getPaper</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="s">"Trade"</span><span class="o">,</span> <span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"paper"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"alice's $900"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"borrowed $900"</span><span class="o">,</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">State</span><span class="o">(</span><span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">900</span><span class="o">),</span> <span class="n">issuer</span><span class="o">),</span> <span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="kc">null</span><span class="o">));</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span> <span class="n">inputPaper</span> <span class="o">=</span> <span class="n">l</span><span class="o">.</span><span class="na">retrieveOutput</span><span class="o">(</span><span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="s">"paper"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's paper"</span><span class="o">,</span> <span class="n">inputPaper</span><span class="o">.</span><span class="na">withOwner</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">()));</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"paper"</span><span class="o">);</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span> <span class="n">inputPaper</span> <span class="o">=</span> <span class="n">l</span><span class="o">.</span><span class="na">retrieveOutput</span><span class="o">(</span><span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="s">"paper"</span><span class="o">);</span> <span class="c1">// We moved a paper to other pubkey.</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"bob's paper"</span><span class="o">,</span> <span class="n">inputPaper</span><span class="o">.</span><span class="na">withOwner</span><span class="o">(</span><span class="n">getBOB_PUBKEY</span><span class="o">()));</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">fails</span><span class="o">();</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> <p>The transactions <code class="docutils literal"><span class="pre">verifies()</span></code> individually, however the state was spent twice! That’s why we need the global ledger verification (<code class="docutils literal"><span class="pre">this.fails()</span></code> at the end). As in previous examples we can use <code class="docutils literal"><span class="pre">tweak</span></code> to create a local copy of the whole ledger:</p> <div class="codeset container"> <div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test fun `chain commercial tweak`() { val issuer = MEGA_CORP.ref(123) ledger { unverifiedTransaction { output("alice's $900", 900.DOLLARS.CASH `issued by` issuer `owned by` ALICE_PUBKEY) } // Some CP is issued onto the ledger by MegaCorp. transaction("Issuance") { output("paper") { getPaper() } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Issue() } timestamp(TEST_TX_TIME) this.verifies() } transaction("Trade") { input("paper") input("alice's $900") output("borrowed $900") { 900.DOLLARS.CASH `issued by` issuer `owned by` MEGA_CORP_PUBKEY } output("alice's paper") { "paper".output<ICommercialPaperState>() `owned by` ALICE_PUBKEY } command(ALICE_PUBKEY) { Cash.Commands.Move() } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this.verifies() } tweak { transaction { input("paper") // We moved a paper to another pubkey. output("bob's paper") { "paper".output<ICommercialPaperState>() `owned by` BOB_PUBKEY } command(MEGA_CORP_PUBKEY) { CommercialPaper.Commands.Move() } this.verifies() } this.fails() } this.verifies() } } </pre></div> </div> <div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span> <span class="kd">public</span> <span class="kt">void</span> <span class="nf">chainCommercialPaperTweak</span><span class="o">()</span> <span class="o">{</span> <span class="n">PartyAndReference</span> <span class="n">issuer</span> <span class="o">=</span> <span class="n">getMEGA_CORP</span><span class="o">().</span><span class="na">ref</span><span class="o">(</span><span class="n">defaultRef</span><span class="o">);</span> <span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span> <span class="n">l</span><span class="o">.</span><span class="na">unverifiedTransaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's $900"</span><span class="o">,</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">State</span><span class="o">(</span><span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">900</span><span class="o">),</span> <span class="n">issuer</span><span class="o">),</span> <span class="n">getALICE_PUBKEY</span><span class="o">(),</span> <span class="kc">null</span><span class="o">));</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="c1">// Some CP is issued onto the ledger by MegaCorp.</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="s">"Issuance"</span><span class="o">,</span> <span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"paper"</span><span class="o">,</span> <span class="n">getPaper</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Issue</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">timestamp</span><span class="o">(</span><span class="n">getTEST_TX_TIME</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="s">"Trade"</span><span class="o">,</span> <span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"paper"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"alice's $900"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"borrowed $900"</span><span class="o">,</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">State</span><span class="o">(</span><span class="n">issuedBy</span><span class="o">(</span><span class="n">DOLLARS</span><span class="o">(</span><span class="mi">900</span><span class="o">),</span> <span class="n">issuer</span><span class="o">),</span> <span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="kc">null</span><span class="o">));</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span> <span class="n">inputPaper</span> <span class="o">=</span> <span class="n">l</span><span class="o">.</span><span class="na">retrieveOutput</span><span class="o">(</span><span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="s">"paper"</span><span class="o">);</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"alice's paper"</span><span class="o">,</span> <span class="n">inputPaper</span><span class="o">.</span><span class="na">withOwner</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">()));</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getALICE_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">Cash</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">tweak</span><span class="o">(</span><span class="n">lw</span> <span class="o">-></span> <span class="o">{</span> <span class="n">lw</span><span class="o">.</span><span class="na">transaction</span><span class="o">(</span><span class="n">tx</span> <span class="o">-></span> <span class="o">{</span> <span class="n">tx</span><span class="o">.</span><span class="na">input</span><span class="o">(</span><span class="s">"paper"</span><span class="o">);</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span> <span class="n">inputPaper</span> <span class="o">=</span> <span class="n">l</span><span class="o">.</span><span class="na">retrieveOutput</span><span class="o">(</span><span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">State</span><span class="o">.</span><span class="na">class</span><span class="o">,</span> <span class="s">"paper"</span><span class="o">);</span> <span class="c1">// We moved a paper to another pubkey.</span> <span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="s">"bob's paper"</span><span class="o">,</span> <span class="n">inputPaper</span><span class="o">.</span><span class="na">withOwner</span><span class="o">(</span><span class="n">getBOB_PUBKEY</span><span class="o">()));</span> <span class="n">tx</span><span class="o">.</span><span class="na">command</span><span class="o">(</span><span class="n">getMEGA_CORP_PUBKEY</span><span class="o">(),</span> <span class="k">new</span> <span class="n">JavaCommercialPaper</span><span class="o">.</span><span class="na">Commands</span><span class="o">.</span><span class="na">Move</span><span class="o">());</span> <span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="o">});</span> <span class="n">lw</span><span class="o">.</span><span class="na">fails</span><span class="o">();</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="n">l</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span> <span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span> <span class="o">});</span> <span class="o">}</span> </pre></div> </div> </div> </div> </div> </div> </div> <footer> <div class="rst-footer-buttons" role="navigation" aria-label="footer navigation"> <a href="tutorial-integration-testing.html" 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