test: use T.TempDir to create temporary test directory

[Juneezee]

Change Description

A testing cleanup.

This pull request replaces ioutil.TempDir with t.TempDir. We can use the T.TempDir function from the testing package to create temporary directory. The directory created by T.TempDir is automatically removed when the test and all its subtests complete.

This saves us at least 2 lines (error check, and cleanup) on every instance, or in some cases adds cleanup that we forgot.

Reference: https://pkg.go.dev/testing#T.TempDir

func TestFoo(t *testing.T) {
	// before
	tmpDir, err := ioutil.TempDir("", "")
	require.NoError(t, err)
	defer os.RemoveAll(tmpDir)

	// now
	tmpDir := t.TempDir()
}

Steps to Test

Changes to existing tests only. The existing testing targets in Makefile and CI cover the changes.

Pull Request Checklist

Testing

• Your PR passes all CI checks.
• Tests covering the positive and negative (error paths) are included.
• Bug fixes contain tests triggering the bug to prevent regressions.

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• The change obeys the Code Documentation and Commenting guidelines, and lines wrap at 80.
• Commits follow the Ideal Git Commit Structure.
• Any new logging statements use an appropriate subsystem and logging level.
• There is a change description in the release notes, or [skip ci] in the commit message for small changes.

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[Juneezee]

Rebased onto master and resolved conflicts.

[Juneezee]

Rebased onto master.

[guggero]

Thanks a lot for the cleanup PR!
I think it makes a lot of sense to make use of this new feature.

To make review easier, would it be possible for you to split this PR into multiple commits, one for each top level package (aliasmgr, cert, chainntnfs, chanbackup, channeldb, ...) and prefix the commits accordingly?

Also an entry in the 0.16 change log file under the "Code health" section (you can create it if it doesn't exist yet) would be nice.

[guggero]

Wow, that was quick! Thanks a lot for the updates.

Looks very good to me. Did a quick search after checking out this PR and found 7 more instances of ioutil.TempFile throughout the codebase. Do we want to fix those as well?
Since it seems mixing t.TempDir() and ioutil.TempFile() can lead to errors.

[guggero]

Thanks a lot for the updates!
Can you work the last two commits into their corresponding previous commits please? Basically split the commits and squash them with the commit for the package they belong in.
Then I'll do a full review on it again.

[guggero]

Hmm, this doesn't seem to fix the flaky failure I mentioned before. It looks like you uncovered a problem with the test itself.
We need to add require.NoError(t, unlockMsg.UnloadWallet()) on Line 608 (directly after service.MacResponseChan <- testMac) to fix the flake.

[guggero]

Thanks for the blazing fast updates! LGTM 🎉

[yyforyongyu]

Very nice! I also like bringing the usage of t.Cleanup, which makes everything cleaner. This is an LGTM👍 Meanwhile, could you rebase this PR? We've added an extra build step and kinda wanna see if this PR passes.

[yyforyongyu]

LGTM🎉