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Inline lambdas passed to assertDoesNotThrows to support suspending functions #2684

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merged 11 commits into from
Aug 17, 2021
Merged

Inline lambdas passed to assertDoesNotThrows to support suspending functions #2684

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3213dcf
Inline lambdas passed to assertDoesNotThrows to support suspending fu…
williamboman Aug 11, 2021
b8154ec
pass explicit type param to avoid unreachable code workaround
williamboman Aug 11, 2021
14407dd
overload function for Nothing return types
williamboman Aug 13, 2021
80aeb8d
remove reified types
williamboman Aug 13, 2021
67cd7a4
Merge remote-tracking branch 'upstream/main' into assert-does-not-thr…
williamboman Aug 13, 2021
de6c87c
move method to below all usage
williamboman Aug 13, 2021
d48eeb4
add dynamic tests
williamboman Aug 13, 2021
69b5a17
add to release notes
williamboman Aug 16, 2021
ba06ff1
Merge remote-tracking branch 'upstream/main' into assert-does-not-thr…
williamboman Aug 16, 2021
5fd5d97
Update documentation/src/docs/asciidoc/release-notes/release-notes-5.…
williamboman Aug 16, 2021
742d7af
s/getThrowingSupplier/evaluateAndWrap/
williamboman Aug 16, 2021
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21 changes: 16 additions & 5 deletions junit-jupiter-api/src/main/kotlin/org/junit/jupiter/api/Assertions.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,14 @@ inline fun <reified T : Throwable> assertThrows(noinline message: () -> String,
}, Supplier(message))
}

@PublishedApi
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https://stackoverflow.com/a/41905907

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Again, possibly dumb question here, but why do we need this method to be inline?

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Also, could you please move this method below the other ones calling it? :)

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@williamboman williamboman Aug 13, 2021 •
edited
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Again, possibly dumb question here, but why do we need this method to be inline?

Because this function is ultimately the one responsible for calling the provided executable. We want to run the executable in the same context as the callsite of assertDoesNotThrow (so that it can suspend, etc.), so we need to make sure the full call stack from assertDoesNotThrow until here uses inlined functions. If we were to remove the inline modifier on this function, we'll get a compiler error in all of the assertDoesNotThrow functions saying that we're violating the inlineability (I totally just made that word up) of the executable argument, and that we need to change the function signature to assertDoesNotThrow(noinline executable: () -> R). Doing so breaks the tests that now calls a suspending function, because the callback is no longer inlined.

edit: This is at least my understanding

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I see! Thanks for the explanation 😄

internal inline fun <R> getThrowingSupplier(executable: () -> R): ThrowingSupplier<R> = try {
val result = executable()
ThrowingSupplier { result }
} catch (throwable: Throwable) {
ThrowingSupplier { throw throwable }
}

/**
* Example usage:
* ```kotlin
Expand All @@ -158,8 +166,8 @@ inline fun <reified T : Throwable> assertThrows(noinline message: () -> String,
* @param R the result type of the [executable]
*/
@API(status = EXPERIMENTAL, since = "5.5")
fun <R> assertDoesNotThrow(executable: () -> R): R =
Assertions.assertDoesNotThrow(ThrowingSupplier(executable))
inline fun <R> assertDoesNotThrow(executable: () -> R): R =
Assertions.assertDoesNotThrow(getThrowingSupplier(executable))

/**
* Example usage:
Expand All @@ -172,7 +180,7 @@ fun <R> assertDoesNotThrow(executable: () -> R): R =
* @param R the result type of the [executable]
*/
@API(status = EXPERIMENTAL, since = "5.5")
fun <R> assertDoesNotThrow(message: String, executable: () -> R): R =
inline fun <R> assertDoesNotThrow(message: String, executable: () -> R): R =
assertDoesNotThrow({ message }, executable)

/**
Expand All @@ -186,8 +194,11 @@ fun <R> assertDoesNotThrow(message: String, executable: () -> R): R =
* @param R the result type of the [executable]
*/
@API(status = EXPERIMENTAL, since = "5.5")
fun <R> assertDoesNotThrow(message: () -> String, executable: () -> R): R =
Assertions.assertDoesNotThrow(ThrowingSupplier(executable), Supplier(message))
inline fun <R> assertDoesNotThrow(noinline message: () -> String, executable: () -> R): R =
Assertions.assertDoesNotThrow(
getThrowingSupplier(executable),
Supplier(message)
)

/**
* Example usage:
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11 changes: 10 additions & 1 deletion junit-jupiter-engine/src/test/kotlin/org/junit/jupiter/api/KotlinAssertionsTests.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -62,12 +62,21 @@ class KotlinAssertionsTests {
}

@Test
fun `expected context exception testing`() = runBlocking<Unit> {
fun `assertThrows with coroutines`() = runBlocking<Unit> {
assertThrows<AssertionError>("Should fail async") {
suspend { fail("Should fail async") }()
}
}

@Test
fun `assertDoesNotThrow with coroutines`() = runBlocking {
val result = assertDoesNotThrow {
suspend { "Result" }()
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We might want to have another test with a suspending function that actually throws an exception (thus making the test fail), since we want to make sure that the assertion is actually waiting for the "throwing"

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Just noticed the test factory below, you could even add one dynamic test in each dynamicContainer for this new suspending function use case :)

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Done! d48eeb4

}

assertEquals("Result", result)
}

@TestFactory
fun assertDoesNotThrow(): Stream<out DynamicNode> = Stream.of(
dynamicContainer("succeeds when no exception thrown", Stream.of(
Expand Down