[#403] print the changes per red commit in stats

To generate a retro file template containing stats about the green and red commits
- implement the TcrEvent.AllLineChangesPerRedCommit
- Refactor some functions
- call the print method on the changes in red commit
- update the tests

src/events/tcr_events.go

@@ -199,20 +199,27 @@ func (events *TcrEvents) AllLineChangesPerCommit() IntAggregates {
 // AllLineChangesPerGreenCommit returns the minimum, average, and maximum number of
 // changed lines per green commit (source and test)
 func (events *TcrEvents) AllLineChangesPerGreenCommit() IntAggregates {
-	passingEvents := eventsWithGreenStatus(events)
+	passingEvents := events.withStatus(StatusPass)
 	return passingEvents.lineChangesPerCommit(allLineChanges)
 }
 
-func allLineChanges(e DatedTcrEvent) int {
-	return e.Event.Changes.All()
+// AllLineChangesPerRedCommit returns the minimum, average, and maximum number of
+// changed lines per red commit (source and test)
+func (events *TcrEvents) AllLineChangesPerRedCommit() IntAggregates {
+	failingEvents := events.withStatus(StatusFail)
+	return failingEvents.lineChangesPerCommit(allLineChanges)
 }
 
-func eventsWithGreenStatus(events *TcrEvents) TcrEvents {
+func (events *TcrEvents) withStatus(status CommandStatus) TcrEvents {
 	return filter(*events, func(event DatedTcrEvent) bool {
-		return event.Event.Status == StatusPass
+		return event.Event.Status == status
 	})
 }
 
+func allLineChanges(e DatedTcrEvent) int {
+	return e.Event.Changes.All()
+}
+
 func filter[T any](slice []T, f func(T) bool) []T {
 	var n []T
 	for _, e := range slice {

src/events/tcr_events_test.go

@@ -444,9 +444,10 @@ func Test_events_time_between_commits(t *testing.T) {
 
 func Test_average_size_of_green_commits(t *testing.T) {
 	testFlags := []struct {
-		desc     string
-		events   TcrEvents
-		expected IntAggregates
+		desc          string
+		events        TcrEvents
+		expectedGreen IntAggregates
+		expectedRed   IntAggregates
 	}{
 		{
 			"1 passing event",
@@ -455,6 +456,7 @@ func Test_average_size_of_green_commits(t *testing.T) {
 				WithModifiedSrcLines(3),
 				WithModifiedTestLines(0))))},
 			IntAggregates{min: 3, avg: 3, max: 3},
+			IntAggregates{min: 0, avg: 0, max: 0},
 		},
 		{
 			"summing all tests and source line changes",
@@ -463,6 +465,7 @@ func Test_average_size_of_green_commits(t *testing.T) {
 				WithModifiedSrcLines(3),
 				WithModifiedTestLines(2))))},
 			IntAggregates{min: 5, avg: 5, max: 5},
+			IntAggregates{min: 0, avg: 0, max: 0},
 		},
 		{
 			"1 passing and 1 failing event",
@@ -476,11 +479,13 @@ func Test_average_size_of_green_commits(t *testing.T) {
 					WithModifiedSrcLines(5),
 					WithModifiedTestLines(0))))},
 			IntAggregates{min: 4, avg: 4, max: 4},
+			IntAggregates{min: 5, avg: 5, max: 5},
 		},
 	}
 	for _, tt := range testFlags {
 		t.Run(tt.desc, func(t *testing.T) {
-			assert.Equal(t, tt.expected, tt.events.AllLineChangesPerGreenCommit())
+			assert.Equal(t, tt.expectedGreen, tt.events.AllLineChangesPerGreenCommit())
+			assert.Equal(t, tt.expectedRed, tt.events.AllLineChangesPerRedCommit())
 		})
 	}
 }

src/stats/printer.go

@@ -44,6 +44,7 @@ func Print(branch string, tcrEvents events.TcrEvents) {
 	printStatMinMaxAvg("Changes per commit (src)", tcrEvents.SrcLineChangesPerCommit())
 	printStatMinMaxAvg("Changes per commit (test)", tcrEvents.TestLineChangesPerCommit())
 	printStatMinMaxAvg("Changes per green commit", tcrEvents.AllLineChangesPerGreenCommit())
+	printStatMinMaxAvg("Changes per red commit", tcrEvents.AllLineChangesPerRedCommit())
 	printStatEvolution("Passing tests count", tcrEvents.PassingTestsEvolution())
 	printStatEvolution("Failing tests count", tcrEvents.FailingTestsEvolution())
 	printStatEvolution("Skipped tests count", tcrEvents.SkippedTestsEvolution())

src/stats/printer_test.go

@@ -202,6 +202,7 @@ func Test_print_all_stats(t *testing.T) {
 		"- Changes per commit (src):  1 (min) / 5 (avg) / 10 (max)",
 		"- Changes per commit (test): 0 (min) / 1.3 (avg) / 3 (max)",
 		"- Changes per green commit:  13 (min) / 13 (avg) / 13 (max)",
+		"- Changes per red commit:    1 (min) / 3 (avg) / 5 (max)",
 		"- Passing tests count:       2 --> 8",
 		"- Failing tests count:       1 --> 2",
 		"- Skipped tests count:       5 --> 1",