Escaped characters detection in literals

[ferranpujolcamins]

Followup of #228, Fixes #230

This PR fixes inline snapshot tests containing special characters. AssertInlineSnapshot now checks whether the snapshot contains special characters or not. If it does, escapes the snapshot literal appropriately.

Known issue: AssertInlineSnapshot still searches only for "" and multiline string literals (it does not search #""" """# for example)

[stephencelis]

Wow @ferranpujolcamins, you took this to the next level!

This is looking really good! I cloned your branch and played around with it and it feels very slick! 😄 Just a few small comments.

Known issue: AssertInlineSnapshot still searches only for "" and multiline string literals (it does not search #""" """# for example)

One interesting side effect is that it'll automatically insert more #s than are needed when re-recording. Do you think you'll have time to address this soon?

[ferranpujolcamins]

Do you think you'll have time to address this soon?

I'm giving it a try

[ferranpujolcamins]

One interesting side effect is that it'll automatically insert more #s than are needed when re-recording

I managed to make it work. Not without pain! Substrings are tricky. Mutating self in AssertInlineSnapshot.replaceFirstOccurrence produced crazy results, I don't exactly know why.

[stephencelis]

Hey @ferranpujolcamins! Looks like we're close but not quite there yet. If you run the following test block:

  func testAny() {
    struct User { let id: Int, name: String, bio: String }
    let user = User(id: 1, name: ##"Bl#""#obby"##, bio: "Blobbed around the world.")
    assertSnapshot(matching: user, as: .dump)
    _assertInlineSnapshot(matching: user, as: .dump, with: #####"""
    """#####)
  }

The leading #####""" correctly becomes ##""", but the trailing """##### ends up appending an extra coupla #s to become """#######. I think the problem is the use of multiLineLiteralEndIndex for replacement, which only matches against """.

The logic you're building on is definitely the most complicated part of the lib, sorry! Let us know if we can help in any way.

[ferranpujolcamins]

I see! This won't be an easy change after all. Let's do this:
I'll open other PRs with small refactors that will make our live easier. My goal is to be able to unit test the inline snapshot feature, so I will separate code transformation from file operartions.

After that, we can keep working on this one.

[ferranpujolcamins]

Would be cool to add swift-prelude as dependency?

[ferranpujolcamins]

Mmmm I see it depends on this package so we can't use it here :(

[ferranpujolcamins]

Ok, I've rebased onto master.
I've added some tests. Your counter example is now working properly.
I still need to add some more, but I'd appreciate early feedback.

The tests work as follows (it's a little bit confusing):
The tests in InlineSnapshotTests assert the correctness of the source file modifications that the inline snapshot test machinery does. To do so, we snapshot test the modified source.

The recorded snapshots, are in turn well formed tests that are added to the test target.

• Thus, we check the source code after an inline snapshot is recorded is valid.
• They assert that the recorded snapshot is escaped properly.
  Please see comment at the end of InlineSnapshotTests.swift.

[stephencelis]

This is really fun stuff! @mbrandonw and I looked over it today and would love to help you land it in any way possible. The subject of the PR is still a "WIP" and you mention that you still have some things you wanted to work on. Can you let us know what they are and how we can unblock you?

[stephencelis]

Just wanna flag this before merging.

[stephencelis]

Cool stuff!

[ferranpujolcamins]

Yeah I just added a couple of tests. Should be ready to merge. If we find some corner case later let's add a regression test!

Thanks guys!

[ferranpujolcamins]

Gentle ping ;)

[stephencelis]

Beautiful work! This'll eliminate a major gotcha for folks. Thanks again for contributing!

[ferranpujolcamins]

Thank you guys for working on this useful project!