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<script type="text/javascript" src="_static/codesets.js"></script><div class="section" id="writing-a-contract-test">
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<h1>Writing a contract test<a class="headerlink" href="#writing-a-contract-test" title="Permalink to this headline">¶</a></h1>
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<p>This tutorial will take you through the steps required to write a contract test using Kotlin and/or Java.</p>
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<p>The testing DSL allows one to define a piece of the ledger with transactions referring to each other, and ways of
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verifying their correctness.</p>
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<div class="section" id="testing-single-transactions">
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<h2>Testing single transactions<a class="headerlink" href="#testing-single-transactions" title="Permalink to this headline">¶</a></h2>
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<p>We start with the empty ledger:</p>
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<div class="codeset container">
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">@Test</span>
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<span class="k">fun</span> <span class="nf">emptyLedger</span><span class="p">()</span> <span class="p">{</span>
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<span class="n">ledger</span> <span class="p">{</span>
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<span class="p">}</span>
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<span class="p">}</span>
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</pre></div>
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</div>
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<div class="highlight-java"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">static</span> <span class="n">com</span><span class="o">.</span><span class="na">r3corda</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>
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<span class="kn">import</span> <span class="nn">static</span> <span class="n">com</span><span class="o">.</span><span class="na">r3corda</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>
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<span class="nd">@Test</span>
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<span class="kd">public</span> <span class="kt">void</span> <span class="nf">emptyLedger</span><span class="o">()</span> <span class="o">{</span>
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<span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span>
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<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>
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<span class="o">});</span>
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<span class="o">}</span>
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</pre></div>
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</div>
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</div>
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<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
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correctness. A ledger is effectively a fresh world with no pre-existing transactions or services within it.</p>
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<p>Let’s add a Cash transaction:</p>
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<div class="codeset container">
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test
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fun simpleCashDoesntCompile() {
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val inState = Cash.State(
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amount = 1000.DOLLARS `issued by` DUMMY_CASH_ISSUER,
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owner = DUMMY_PUBKEY_1
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)
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ledger {
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transaction {
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input(inState)
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}
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}
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}
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</pre></div>
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</div>
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<div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span>
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<span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCashDoesntCompile</span><span class="o">()</span> <span class="o">{</span>
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<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inState</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>
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<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">getDUMMY_CASH_ISSUER</span><span class="o">()),</span>
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<span class="n">getDUMMY_PUBKEY_1</span><span class="o">()</span>
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<span class="o">);</span>
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<span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span>
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<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>
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<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>
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<span class="o">});</span>
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<span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span>
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<span class="o">});</span>
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<span class="o">}</span>
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</pre></div>
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</div>
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</div>
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<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
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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>
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<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
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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
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ledger (that won’t be verified) which outputs the specified state, and references that from this transaction.</p>
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<p>The above code however doesn’t compile:</p>
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<div class="codeset container">
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">Error</span><span class="p">:(</span><span class="m">26</span><span class="p">,</span> <span class="m">21</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>
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</pre></div>
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</div>
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<div class="highlight-java"><div class="highlight"><pre><span></span><span class="nl">Error:</span><span class="o">(</span><span class="mi">26</span><span class="o">,</span> <span class="mi">31</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>
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</pre></div>
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</div>
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</div>
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<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
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last line of <code class="docutils literal"><span class="pre">transaction</span></code>:</p>
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<div class="codeset container">
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|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test
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fun simpleCash() {
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|
val inState = Cash.State(
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amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
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owner = DUMMY_PUBKEY_1
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)
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ledger {
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|
transaction {
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|
input(inState)
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|
this.verifies()
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|
}
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|
}
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|
}
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|
</pre></div>
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</div>
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<div class="highlight-java"><div class="highlight"><pre><span></span><span class="nd">@Test</span>
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|
<span class="kd">public</span> <span class="kt">void</span> <span class="nf">simpleCash</span><span class="o">()</span> <span class="o">{</span>
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|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inState</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>
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|
<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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
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|
<span class="n">getDUMMY_PUBKEY_1</span><span class="o">()</span>
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|
<span class="o">);</span>
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|
<span class="n">ledger</span><span class="o">(</span><span class="n">l</span> <span class="o">-></span> <span class="o">{</span>
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|
<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>
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|
<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>
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<span class="k">return</span> <span class="n">tx</span><span class="o">.</span><span class="na">verifies</span><span class="o">();</span>
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|
<span class="o">});</span>
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|
<span class="k">return</span> <span class="n">Unit</span><span class="o">.</span><span class="na">INSTANCE</span><span class="o">;</span>
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|
<span class="o">});</span>
|
|
<span class="o">}</span>
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|
</pre></div>
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</div>
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</div>
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<p>The code finally compiles. When run, it produces the following error:</p>
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|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span>com.r3corda.core.contracts.TransactionVerificationException$ContractRejection: java.lang.IllegalArgumentException: Failed requirement: for deposit [01] at issuer Snake Oil Issuer the amounts balance
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|
</pre></div>
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</div>
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|
<div class="admonition note">
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|
<p class="first admonition-title">Note</p>
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|
<p class="last">The reference here to the ‘Snake Oil Issuer’ is because we are using the pre-canned <code class="docutils literal"><span class="pre">DUMMY_CASH_ISSUER</span></code>
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|
identity as the issuer of our cash.</p>
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</div>
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|
<p>The transaction verification failed, because the sum of inputs does not equal the sum of outputs. We can specify that
|
|
this is 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">amounts</span> <span class="pre">balance"</span></code>:</p>
|
|
<div class="codeset container">
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test
|
|
fun simpleCashFailsWith() {
|
|
val inState = Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = DUMMY_PUBKEY_1
|
|
)
|
|
ledger {
|
|
transaction {
|
|
input(inState)
|
|
this `fails with` "the amounts balance"
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|
}
|
|
}
|
|
}
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|
</pre></div>
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</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">simpleCashFailsWith</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inState</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getDUMMY_PUBKEY_1</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">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">failsWith</span><span class="o">(</span><span class="s">"the amounts balance"</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 simpleCashSuccess() {
|
|
val inState = Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = DUMMY_PUBKEY_1
|
|
)
|
|
ledger {
|
|
transaction {
|
|
input(inState)
|
|
this `fails with` "the amounts balance"
|
|
output(inState.copy(owner = DUMMY_PUBKEY_2))
|
|
command(DUMMY_PUBKEY_1) { Cash.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">simpleCashSuccess</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inState</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getDUMMY_PUBKEY_1</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">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">failsWith</span><span class="o">(</span><span class="s">"the amounts balance"</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="n">inState</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inState</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_2</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">getDUMMY_PUBKEY_1</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="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">DUMMY_PUBKEY_2</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">DUMMY_PUBKEY_1</span></code>.</p>
|
|
<p>We constructed a complete signed cash transaction from <code class="docutils literal"><span class="pre">DUMMY_PUBKEY_1</span></code> to <code class="docutils literal"><span class="pre">DUMMY_PUBKEY_2</span></code> 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 ruin the transaction for good... 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 simpleCashTweakSuccess() {
|
|
val inState = Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = DUMMY_PUBKEY_1
|
|
)
|
|
ledger {
|
|
transaction {
|
|
input(inState)
|
|
this `fails with` "the amounts balance"
|
|
output(inState.copy(owner = DUMMY_PUBKEY_2))
|
|
|
|
tweak {
|
|
command(DUMMY_PUBKEY_2) { Cash.Commands.Move() }
|
|
this `fails with` "the owning keys are the same as the signing keys"
|
|
}
|
|
|
|
command(DUMMY_PUBKEY_1) { Cash.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">simpleCashTweakSuccess</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inState</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getDUMMY_PUBKEY_1</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">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">failsWith</span><span class="o">(</span><span class="s">"the amounts balance"</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="n">inState</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inState</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_2</span><span class="o">()));</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_2</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="k">return</span> <span class="n">tw</span><span class="o">.</span><span class="na">failsWith</span><span class="o">(</span><span class="s">"the owning keys are the same as the signing keys"</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">getDUMMY_PUBKEY_1</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="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 allows the local “ruining” of the transaction 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 toplevel <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 simpleCashTweakSuccessTopLevelTransaction() {
|
|
val inState = Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = DUMMY_PUBKEY_1
|
|
)
|
|
transaction {
|
|
input(inState)
|
|
this `fails with` "the amounts balance"
|
|
output(inState.copy(owner = DUMMY_PUBKEY_2))
|
|
|
|
tweak {
|
|
command(DUMMY_PUBKEY_2) { Cash.Commands.Move() }
|
|
this `fails with` "the owning keys are the same as the signing keys"
|
|
}
|
|
|
|
command(DUMMY_PUBKEY_1) { Cash.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">simpleCashTweakSuccessTopLevelTransaction</span><span class="o">()</span> <span class="o">{</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inState</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getDUMMY_PUBKEY_1</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">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">failsWith</span><span class="o">(</span><span class="s">"the amounts balance"</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="n">inState</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inState</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_2</span><span class="o">()));</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_2</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="k">return</span> <span class="n">tw</span><span class="o">.</span><span class="na">failsWith</span><span class="o">(</span><span class="s">"the owning keys are the same as the signing keys"</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">getDUMMY_PUBKEY_1</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="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 chainCash() {
|
|
ledger {
|
|
unverifiedTransaction {
|
|
output("MEGA_CORP cash") {
|
|
Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = MEGA_CORP_PUBKEY
|
|
)
|
|
}
|
|
}
|
|
|
|
transaction {
|
|
input("MEGA_CORP cash")
|
|
output("MEGA_CORP cash".output<Cash.State>().copy(owner = DUMMY_PUBKEY_1))
|
|
command(MEGA_CORP_PUBKEY) { Cash.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">chainCash</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">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">"MEGA_CORP cash"</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getMEGA_CORP_PUBKEY</span><span class="o">()</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="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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inputCash</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">Cash</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">"MEGA_CORP cash"</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="n">inputCash</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_1</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">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="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">MEGA_CORP</span></code> has a thousand dollars 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>The <code class="docutils literal"><span class="pre">output</span></code> cash was labelled with <code class="docutils literal"><span class="pre">"MEGA_CORP</span> <span class="pre">cash"</span></code>, we can subsequently referred to this other transactions, e.g.
|
|
by <code class="docutils literal"><span class="pre">input("MEGA_CORP</span> <span class="pre">cash")</span></code> or <code class="docutils literal"><span class="pre">"MEGA_CORP</span> <span class="pre">cash".output<Cash.State>()</span></code>.</p>
|
|
<p>What happens if we reuse the output cash twice?</p>
|
|
<div class="codeset container">
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span>@Test
|
|
fun chainCashDoubleSpend() {
|
|
ledger {
|
|
unverifiedTransaction {
|
|
output("MEGA_CORP cash") {
|
|
Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = MEGA_CORP_PUBKEY
|
|
)
|
|
}
|
|
}
|
|
|
|
transaction {
|
|
input("MEGA_CORP cash")
|
|
output("MEGA_CORP cash".output<Cash.State>().copy(owner = DUMMY_PUBKEY_1))
|
|
command(MEGA_CORP_PUBKEY) { Cash.Commands.Move() }
|
|
this.verifies()
|
|
}
|
|
|
|
transaction {
|
|
input("MEGA_CORP cash")
|
|
// We send it to another pubkey so that the transaction is not identical to the previous one
|
|
output("MEGA_CORP cash".output<Cash.State>().copy(owner = DUMMY_PUBKEY_2))
|
|
command(MEGA_CORP_PUBKEY) { Cash.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">chainCashDoubleSpend</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">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">"MEGA_CORP cash"</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getMEGA_CORP_PUBKEY</span><span class="o">()</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="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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inputCash</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">Cash</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">"MEGA_CORP cash"</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="n">inputCash</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_1</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">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="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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inputCash</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">Cash</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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="c1">// We send it to another pubkey so that the transaction is not identical to the previous one</span>
|
|
<span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_2</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">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="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>The transactions <code class="docutils literal"><span class="pre">verifies()</span></code> individually, however the state was spent twice!</p>
|
|
<p>We can also verify the complete ledger by calling <code class="docutils literal"><span class="pre">verifies</span></code>/<code class="docutils literal"><span class="pre">fails</span></code> on the ledger level. We can also 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 chainCashDoubleSpendFailsWith() {
|
|
ledger {
|
|
unverifiedTransaction {
|
|
output("MEGA_CORP cash") {
|
|
Cash.State(
|
|
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
|
|
owner = MEGA_CORP_PUBKEY
|
|
)
|
|
}
|
|
}
|
|
|
|
transaction {
|
|
input("MEGA_CORP cash")
|
|
output("MEGA_CORP cash".output<Cash.State>().copy(owner = DUMMY_PUBKEY_1))
|
|
command(MEGA_CORP_PUBKEY) { Cash.Commands.Move() }
|
|
this.verifies()
|
|
}
|
|
|
|
tweak {
|
|
transaction {
|
|
input("MEGA_CORP cash")
|
|
// We send it to another pubkey so that the transaction is not identical to the previous one
|
|
output("MEGA_CORP cash".output<Cash.State>().copy(owner = DUMMY_PUBKEY_1))
|
|
command(MEGA_CORP_PUBKEY) { Cash.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">chainCashDoubleSpendFailsWith</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">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">"MEGA_CORP cash"</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">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="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">,</span> <span class="o">(</span><span class="kt">byte</span><span class="o">)</span><span class="mi">1</span><span class="o">)),</span>
|
|
<span class="n">getMEGA_CORP_PUBKEY</span><span class="o">()</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="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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inputCash</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">Cash</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">"MEGA_CORP cash"</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="n">inputCash</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_1</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">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="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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="n">Cash</span><span class="o">.</span><span class="na">State</span> <span class="n">inputCash</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">Cash</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">"MEGA_CORP cash"</span><span class="o">);</span>
|
|
<span class="c1">// We send it to another pubkey so that the transaction is not identical to the previous one</span>
|
|
<span class="n">tx</span><span class="o">.</span><span class="na">output</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">copy</span><span class="o">(</span><span class="n">inputCash</span><span class="o">.</span><span class="na">getAmount</span><span class="o">(),</span> <span class="n">getDUMMY_PUBKEY_2</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">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="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>
|
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</div>
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