Track double writes (prepare for literal snapshots).

[nedtwigg]

Implementation of

• Policy for when to read vs write snapshots #12.

Also the very beginnings of inline literal snapshots.

@jknack I'm hoping that you will write the whole literal snapshot system if you're interested in it. This PR is the first step of that feature. It's a good next step after #13 gets finished.

[jknack]

@nedtwigg was expecting some tests to fail, like: DuplicateWriteTest but it doesn't. What else need to be done here?

[jknack]

@nedtwigg can we merge this?

[nedtwigg]

This test is expected to fail, and in fact it is failing with:

org.opentest4j.AssertionFailedError: Snapshot was set to multiple values:
first time:com.diffplug.selfie.junit5.CallStack@6d5620ce

this time:com.diffplug.selfie.junit5.CallStack@311bf055
	at app//com.diffplug.selfie.junit5.WriteTracker.recordInternal(WriteTracker.kt:53)
	at app//com.diffplug.selfie.junit5.DiskWriteTracker.record(WriteTracker.kt:67)
	at app//com.diffplug.selfie.junit5.ClassProgress.write(SelfieTestExecutionListener.kt:151)
	at app//com.diffplug.selfie.junit5.Router.readOrWriteOrKeep(SelfieTestExecutionListener.kt:49)
	at app//com.diffplug.selfie.DiskSelfie.toMatchDisk(Selfie.kt:37)
	at app//com.diffplug.selfie.DiskSelfie.toMatchDisk$default(Selfie.kt:36)
	at app//undertest.junit5.UT_DuplicateWriteTest.shouldFail(UT_DuplicateWriteTest.kt:9)
	at [email protected]/java.lang.reflect.Method.invoke(Method.java:568)
	at [email protected]/java.util.ArrayList.forEach(ArrayList.java:1511)
	at [email protected]/java.util.ArrayList.forEach(ArrayList.java:1511)

We should make assertions about the error message (e.g. the current error message is not great).

Same thing is true of the writeonce_mode test below. It is supposed to fail, and it is, but we are not making any assertions about what the failure should be, which means it's hard for us to have good failure messages.

I'm not sure what the best way to make these assertions is. It's easy to catch an exception in the UT_ build and make the assertions there. The alternative is to parse the JUnit test result and pull the assertions into the "puppetmaster" build. No opinion which way to go, just that the message should have an assertion against it.

Once we are making assertions on the error message somehow, this PR is ready to merge, and you can move on to

• Carriage return handling #16
• and then literal snapshots

• selfie/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/Selfie.kt

  Lines 71 to 75 in 837c2b4

  	class IntSelfie(private val actual: Int) {
  	fun toBe(expected: Int): Int = TODO()
  	fun toBe_TODO(): Int = TODO()
  	}
  	fun expectSelfie(actual: Int) = IntSelfie(actual)

[nedtwigg]

Sorry, I had this review comment stuck as pending. Yes you can merge this if you want, but we'll need to revisit it to make sure we're doing assertions on the error messages somehow. I think most natural to do in this PR, but we could do that in a future PR too.

[jknack]

@nedtwigg updated with nice error handling/stacktraces.

[nedtwigg]

Amazing! I love your solution. Next up:

• Carriage return handling #16
• then in-place snapshot writing, I would start with either integers or binary, whichever you prefer.

selfie/selfie-runner-junit5/src/main/kotlin/com/diffplug/selfie/Selfie.kt

Lines 65 to 75 in 837c2b4

	class BinarySelfie(private val actual: ByteArray) : DiskSelfie(Snapshot.of(actual)) {
	fun toBeBase64(expected: String): ByteArray = TODO()
	fun toBeBase64_TODO(): ByteArray = TODO()
	}
	fun expectSelfie(actual: ByteArray) = BinarySelfie(actual)
	class IntSelfie(private val actual: Int) {
	fun toBe(expected: Int): Int = TODO()
	fun toBe_TODO(): Int = TODO()
	}
	fun expectSelfie(actual: Int) = IntSelfie(actual)