Improve promotion comment. (#31)

* Improve promotion comment.

Promotion comment used to list all the values in the 'targetPaths' key,
ignoring the promotionAllow and promotionBlock lists. This PR limits
the comment to only paths that are being promoted.

* Use testify library for assert

* return nil, use assert

* Add t.Parallel()

internal/pkg/githubapi/github.go

@@ -1109,14 +1109,40 @@ func prBody(keys []int, newPrMetadata prMetadata, newPrBody string) string {
 
 	for i, k := range keys {
 		sp = newPrMetadata.PreviousPromotionMetadata[k].SourcePath
-		x := newPrMetadata.PreviousPromotionMetadata[k].TargetPaths
+		x := identifyCommonPaths(newPrMetadata.PromotedPaths, newPrMetadata.PreviousPromotionMetadata[k].TargetPaths)
 		tp = strings.Join(x, fmt.Sprintf("`  \n%s`", strings.Repeat(mkTab, i+1)))
 		newPrBody = newPrBody + fmt.Sprintf("%s↘️  #%d  `%s` ➡️  \n%s`%s`  \n", strings.Repeat(mkTab, i), k, sp, strings.Repeat(mkTab, i+1), tp)
 	}
 
 	return newPrBody
 }
 
+// identifyCommonPaths takes a slice of promotion paths and target paths and
+// returns a slice containing paths in common.
+func identifyCommonPaths(promotionPaths []string, targetPaths []string) []string {
+	if (len(promotionPaths) == 0) || (len(targetPaths) == 0) {
+		return nil
+	}
+	var commonPaths []string
+	for _, pp := range promotionPaths {
+		if pp == "" {
+			continue
+		}
+		for _, tp := range targetPaths {
+			if tp == "" {
+				continue
+			}
+			// strings.HasPrefix is used to check that the target path and promotion path match instead of
+			// using 'pp ==  tp' because the promotion path is targetPath + component.
+			if strings.HasPrefix(pp, tp) {
+				commonPaths = append(commonPaths, tp)
+			}
+		}
+	}
+
+	return commonPaths
+}
+
 func createPrObject(ghPrClientDetails GhPrClientDetails, newBranchRef string, newPrTitle string, newPrBody string, defaultBranch string, assignee string) (*github.PullRequest, error) {
 	newPrConfig := &github.NewPullRequest{
 		Body:  github.String(newPrBody),

internal/pkg/githubapi/github_test.go

@@ -235,6 +235,9 @@ func TestPrBody(t *testing.T) {
 	t.Parallel()
 	keys := []int{1, 2, 3}
 	newPrMetadata := prMetadata{
+		// note: "targetPath3" is missing from the list of promoted paths, so it should not
+		// be included in the new PR body.
+		PromotedPaths: []string{"targetPath1", "targetPath2", "targetPath4", "targetPath5", "targetPath6"},
 		PreviousPromotionMetadata: map[int]promotionInstanceMetaData{
 			1: {
 				SourcePath:  "sourcePath1",
@@ -338,3 +341,72 @@ func TestCommitStatusTargetURL(t *testing.T) {
 		})
 	}
 }
+
+func Test_identifyCommonPaths(t *testing.T) {
+	t.Parallel()
+	type args struct {
+		promoPaths  []string
+		targetPaths []string
+	}
+	tests := []struct {
+		name string
+		args args
+		want []string
+	}{
+		{
+			name: "same paths",
+			args: args{
+				promoPaths:  []string{"path1/component/path", "path2/component/path", "path3/component/path"},
+				targetPaths: []string{"path1", "path2", "path3"},
+			},
+			want: []string{"path1", "path2", "path3"},
+		},
+		{
+			name: "paths1 is empty",
+			args: args{
+				promoPaths:  []string{},
+				targetPaths: []string{"path1", "path2", "path3"},
+			},
+			want: nil,
+		},
+		{
+			name: "paths2 is empty",
+			args: args{
+				promoPaths:  []string{"path1/component/some", "path2/some/other", "path3"},
+				targetPaths: []string{},
+			},
+			want: nil,
+		},
+		{
+			name: "paths2 missing elements",
+			args: args{
+				promoPaths:  []string{"path1", "path2", "path3"},
+				targetPaths: []string{""},
+			},
+			want: nil,
+		},
+		{
+			name: "path1 missing elements",
+			args: args{
+				promoPaths:  []string{""},
+				targetPaths: []string{"path1", "path2"},
+			},
+			want: nil,
+		},
+		{
+			name: "path1 and path2 common elements",
+			args: args{
+				promoPaths:  []string{"path1/component/path", "path3/component/also"},
+				targetPaths: []string{"path1", "path2", "path3"},
+			},
+			want: []string{"path1", "path3"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			got := identifyCommonPaths(tt.args.promoPaths, tt.args.targetPaths)
+			assert.Equal(t, got, tt.want)
+		})
+	}
+}

internal/pkg/githubapi/testdata/pr_body.golden.md

@@ -2,7 +2,6 @@
     `targetPath1`  
     `targetPath2`  
     ↘️  #2  `sourcePath2` ➡️  
-        `targetPath3`  
         `targetPath4`  
         ↘️  #3  `sourcePath3` ➡️  
             `targetPath5`