Write SPR messages to a dedicated block inside commit messages

[rohan-mehta]

This fixes #435 (and also #427).

What/why

As noted in the issue, git spr update can overwrite changes made to the PR title/description. To fix this, we can have a dedicated block that looks like this, which the code can search for.

<!-- SPR data start: please do NOT edit this section -->
  
<!-- SPR data end -->

This way, any edits outside of this block are ignored. Since the block uses comments, it visually looks the same as before. And finally, if no block is present (e.g. on first commit or deleted by a user), it appends to the end.

Test plan

I added new test cases. In addition, I ran a manual test which you can see in https://github.com/rohan-mehta/spr-test-repo. The process was:

1. Create 3 commits, commit_1, commit_2, commit_3, run git spr update, ensure that the spr stack description shows up.
2. Edit the PR for commit_1 (add stuff above the block) and commit_2 (add stuff above and below the block), then re-run git spr update and ensure that nothing is overwritten.
3. Amend commit_2, re-run git spr update and ensure that nothing is overwritten.
4. Create commit_4 at the top of the stack, re-run git spr update and ensure that (a) a new PR is created (b) all previous PRs are updated to show the new commit (c) edits aren't overwritten

[rohan-mehta]

The new version of goreleaser changed this flag (See #427)

[kwk]

See #444 for a standalone PR that addresses this. This PR has many unrelated YAML changes that make it hard to be properly reviewed IMHO.

[kwk]

Thank you for this contribution. Please remove the changes in readme.md and take a look at my test suggestion. The changes to .goreleaser.yml look irrelevant for the most part, so they should not be part of this PR. I've isolated changes in #444 that address problems with gorleaser 2.7. Maybe you can review this?

[kwk]

See #444 for a standalone PR that addresses this. This PR has many unrelated YAML changes that make it hard to be properly reviewed IMHO.

[kwk]

I suggest to use subtests to simplify the naming of variables and be able to focus more on the task than on the naming. I've added a sub-test which I think was missing: when there trimmed body is empty. I didn't run the tests but I hope they work as expected.

Suggested change

	func TestEmbedSprDescription(t *testing.T) {
	existingBody := `# Some User Heading
	User paragraph that should remain untouched.
	<!-- SPR data start: please do NOT edit this section -->
	old spr content
	<!-- SPR data end -->
	Another user paragraph that should remain untouched as well.
	`
	newSpr := `updated spr content with new data`
	want := `# Some User Heading
	User paragraph that should remain untouched.
	<!-- SPR data start: please do NOT edit this section -->
	updated spr content with new data
	<!-- SPR data end -->
	Another user paragraph that should remain untouched as well.`
	got := embedSprDescription(existingBody, newSpr)
	if got != want {
	t.Fatalf("Unexpected embedSprDescription result.\nGot:\n`%s`\n\nWant:\n`%s`\n", got, want)
	}
	// Test if markers are missing, we append them
	existingBodyNoMarkers := `# Some User Heading
	No markers here.
	`
	wantNoMarkers := `# Some User Heading
	No markers here.
	<!-- SPR data start: please do NOT edit this section -->
	updated spr content with new data
	<!-- SPR data end -->`
	gotNoMarkers := embedSprDescription(existingBodyNoMarkers, newSpr)
	if gotNoMarkers != wantNoMarkers {
	t.Fatalf("Unexpected embedSprDescription result when markers are missing.\nGot:\n%s\n\nWant:\n%s\n", gotNoMarkers, wantNoMarkers)
	}
	}
	func TestEmbedSprDescription(t *testing.T) {
	newSpr := `updated spr content with new data`
	t.Run("Update with existing spr content", func(t *testing.T) {
	existingBody := `# Some User Heading
	User paragraph that should remain untouched.
	<!-- SPR data start: please do NOT edit this section -->
	old spr content
	<!-- SPR data end -->
	Another user paragraph that should remain untouched as well.
	`
	want := `# Some User Heading
	User paragraph that should remain untouched.
	<!-- SPR data start: please do NOT edit this section -->
	updated spr content with new data
	<!-- SPR data end -->
	Another user paragraph that should remain untouched as well.`
	got := embedSprDescription(existingBody, newSpr)
	if got != want {
	t.Fatalf("\nGot:\n%s\n\nWant:\n%s\n", got, want)
	}
	})
	t.Run("No spr markers but body", func(t *testing.T) {
	// Test if markers are missing, we append them
	existingBody := `# Some User Heading
	No markers here.
	`
	want := `# Some User Heading
	No markers here.
	<!-- SPR data start: please do NOT edit this section -->
	updated spr content with new data
	<!-- SPR data end -->`
	got := embedSprDescription(existingBody, newSpr)
	if got != want {
	t.Fatalf("\nGot:\n%s\n\nWant:\n%s\n", got, want)
	}
	})
	t.Run("No spr markers and empty body", func(t *testing.T) {
	// Test if markers are missing, we append them
	existingBody := " "
	want := `
	<!-- SPR data start: please do NOT edit this section -->
	updated spr content with new data
	<!-- SPR data end -->`
	got := embedSprDescription(existingBody, newSpr)
	if got != want {
	t.Fatalf("\nGot:\n%s\n\nWant:\n%s\n", got, want)
	}
	})
	}

[kwk]

Why include this in this PR?