snapshotDiff between two single line strings output null

[allotrop3]

Code:

expect(snapshotDiff("foo", "bar")).toMatchSnapshot();

Result:

Received value
    Snapshot Diff:
    null

It seems adding a new line to the end of both arguments results in a valid snapshot diff.

Code

expect(snapshotDiff("foo" + "\n", "bar" + "\n")).toMatchSnapshot();

Result

Received value
    Snapshot Diff:
    - First value
    + Second value

    - foo
    + bar

[thymikee]

Hm, maybe we should add the newline implicitly if there's none? I'm not sure why it doesn't work in general though, anyone mind investigating?

[pedrottimark]

Let’s see if it works correctly after #21 because of jestjs/jest#4520

EDIT: It looks like it is necessary to add newline if both strings are single line, see:
https://github.com/facebook/jest/blob/master/packages/jest-diff/src/index.js#L89-L95