feat: go template function uniqueOlderCommits/uniqueNewerCommits is available

[ikedam]

• They allow to remove duplicated log entries.

Closes #29

What does this do / why do we need it?

• Introduce new go template custom functions uniqueOlderCommits and uniqueNewerCommits. They removes duplicated commits / log entries. "Duplicated" is evaluated with fields specified. For example, if your changelog entries consists of .Scope and .Subject, (uniqueOlderCommits .Commits "Scope" "Subject") is expected.
• There are cases log entries are duplicated. See Expect to filter duplicate commits! #29. We had to write really complicated go templates to remove those duplication. These new functions let us do that easily.

We can rewrite .chglog/CHANGELOG.tpl.md in git-chglog like this:

diff --git a/.chglog/CHANGELOG.tpl.md b/.chglog/CHANGELOG.tpl.md
index 5683d03..db302fe 100755
--- a/.chglog/CHANGELOG.tpl.md
+++ b/.chglog/CHANGELOG.tpl.md
@@ -5,7 +5,7 @@
 {{ if .Unreleased.CommitGroups -}}
 {{ range .Unreleased.CommitGroups -}}
 ### {{ .Title }}
-{{ range .Commits -}}
+{{ range (uniqueOlderCommits .Commits "Scope" "Subject") -}}
 - {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }}
 {{ end }}
 {{ end -}}
@@ -17,7 +17,7 @@
 ## {{ if .Tag.Previous }}[{{ .Tag.Name }}]{{ else }}{{ .Tag.Name }}{{ end }} - {{ datetime "2006-01-02" .Tag.Date }}
 {{ range .CommitGroups -}}
 ### {{ .Title }}
-{{ range .Commits -}}
+{{ range (uniqueOlderCommits .Commits "Scope" "Subject") -}}
 - {{ if .Scope }}**{{ .Scope }}:** {{ end }}{{ .Subject }}
 {{ end }}
 {{ end -}}

How this PR fixes the problem?

• The underlying problem of Expect to filter duplicate commits! #29 is:
  • We have to filter Commit to remove duplication.
  • But it's really difficult to handle structured data with go template: Sprig doesn't work for structured data. Go template doesn't provide mechanisms like lambda functions.
  • What we want to do is: Detect duplication only with specific fields in Commit. For example, "Scope" and "Subject". Or it may be JiraIssueID (for the case only one entry for one ticket).
• I believe uniqueOlderCommits and uniqueNewerCommits resolves that.

What should your reviewer look out for in this PR?

• Let me know if better function names.
• Please propose better descriptions in README.md. This feature is too complicated for my English.

Check lists

• Test passed
• Coding style (indentation, etc)

Additional Comments (if any)

• Older and Newer means the commit order. I believe we also need fix: the sort order of commits is unstable #210 to have this feature fully functioned.
• This code isn't good in performance (O(n^2)). But this doesn't need so much performance and I believe it's better to keep easy to read and easy to maintenance.

Which issue(s) does this PR fix?

fixes #29

[mavogel]

@ikedam thank you for the PR. Could you rebase it onto the latest master?

[ikedam]

@mavogel Sounds strange. I can't get what you want.
This doesn't conflict with the current master and there looks no need to rebase. Why do you want this rebased?

[mavogel]

hi @ikedam to see of the tests and linting still pass with the updated versions of the master, for e.g. golang, golangci-lint, etc. :)

[ikedam]

@mavogel
I believe that should be verified with CI.
Problems on CI? Somehow lint and tests doesn't seem run, but I can't see what happen. Rebase is required to run CI?

[mavogel]

I believe that should be verified with CI.
Exactly yes, in this branch. However, weird, that CI is not triggered

[ikedam]

Let's try reopen.

[ikedam]

Hmm... not triggered. OK. I'll rebase this.

[ikedam]

https://github.com/git-chglog/git-chglog/actions/runs/3995523177

This workflow is awaiting approval from a maintainer in #211

[ikedam]

https://github.blog/changelog/2021-04-22-github-actions-maintainers-must-approve-first-time-contributor-workflow-runs/

[ikedam]

But the message changed to

1 workflow awaiting approval First-time contributors need a maintainer to approve running workflows. Learn more.

and differs from the one before rebasing. Something wrong looked happen inside github.

Anyway, rebase completed.

[mavogel]

ah now I got the approve run button and pushed it :)

[coveralls]

Pull Request Test Coverage Report for Build 3995523177

• 82 of 87 (94.25%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.6%) to 77.395%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
chglog.go	66	71	92.96%

Totals
Change from base Build 3993620083:	0.6%
Covered Lines:	1931
Relevant Lines:	2495

---

💛 - Coveralls