feat: Return git-semver log results in historically descanding order

* Code will fall back to time-based order if history is not fully available

Author: PSanetra

git_utils/sort_commits_desc.go

@@ -2,8 +2,17 @@ package git_utils
 
 import "gopkg.in/src-d/go-git.v4/plumbing/object"
 
-type ByCommitTimeDesc []*object.Commit
+type ByHistoryDesc []*object.Commit
 
-func (a ByCommitTimeDesc) Len() int           { return len(a) }
-func (a ByCommitTimeDesc) Less(i, j int) bool { return a[i].Committer.When.After(a[j].Committer.When) }
-func (a ByCommitTimeDesc) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a ByHistoryDesc) Len() int { return len(a) }
+func (a ByHistoryDesc) Less(i, j int) bool {
+	// Swap i and j as we want to sort descanding
+	isAncestor, err := a[j].IsAncestor(a[i])
+
+	if err != nil {
+		return a[j].Committer.When.Before(a[i].Committer.When)
+	}
+
+	return isAncestor
+}
+func (a ByHistoryDesc) Swap(i, j int) { a[i], a[j] = a[j], a[i] }

integration_tests/src/test/java/de/psanetra/gitsemver/LogCmdTests.java

@@ -239,10 +239,6 @@ public void shouldPrintLogAsConventionalCommits() {
 
             assertThat(container.exec("git", "semver", "log", "--conventional-commits"))
                 .isEqualTo("[\n"
-                    + "  {\n"
-                    + "    \"type\": \"feat\",\n"
-                    + "    \"description\": \"Add feature\"\n"
-                    + "  },\n"
                     + "  {\n"
                     + "    \"type\": \"fix\",\n"
                     + "    \"scope\": \"some_component\",\n"
@@ -257,6 +253,10 @@ public void shouldPrintLogAsConventionalCommits() {
                     + "        \"http://issues.example.com/123\"\n"
                     + "      ]\n"
                     + "    }\n"
+                    + "  },\n"
+                    + "  {\n"
+                    + "    \"type\": \"feat\",\n"
+                    + "    \"description\": \"Add feature\"\n"
                     + "  }\n"
                     + "]\n"
                 );

version_log/version_log.go

@@ -111,7 +111,7 @@ func VersionLog(options VersionLogOptions) ([]*object.Commit, error) {
 		commits = append(commits, commit)
 	}
 
-	sort.Sort(git_utils.ByCommitTimeDesc(commits))
+	sort.Sort(git_utils.ByHistoryDesc(commits))
 
 	// Return most recent commits first
 	return commits, nil