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< 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/or 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 = "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 >
< / 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" > 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 >
< 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 >
< 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
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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 >
< div class = "codeset container" >
< div class = "highlight-kotlin" > < div class = "highlight" > < pre > < span > < / span > @Test
fun simpleCashDoesntCompile() {
val inState = Cash.State(
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amount = 1000.DOLLARS `issued by` DUMMY_CASH_ISSUER,
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owner = DUMMY_PUBKEY_1
)
ledger {
transaction {
input(inState)
}
}
}
< / 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" > simpleCashDoesntCompile< / 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 >
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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 >
< 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" > 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 >
< / 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" > 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 >
< / 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 > @Test
fun simpleCash() {
val inState = Cash.State(
amount = 1000.DOLLARS `issued by` MEGA_CORP.ref(1, 1),
owner = DUMMY_PUBKEY_1
)
ledger {
transaction {
input(inState)
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" > simpleCash< / 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" > 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 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 >
< / div >
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< div class = "admonition note" >
< p class = "first admonition-title" > Note< / p >
< 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 >
identity as the issuer of our cash.< / p >
< / 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"
}
}
}
< / 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" > 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 >
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