[#403] Add stats for all line changes per green commit

To generate a retro file template containing stats about the green and red commits
- add ChangedLines.All()
- add TcrEvents.AllLineChangesPerGreenCommit()
- Refactor in TcrEvents
- add tests

src/events/tcr_event.go

@@ -54,6 +54,11 @@ type (
 	}
 )
 
+// All returns the sum of all line changes, from both test and source
+func (l ChangedLines) All() int {
+	return l.Src + l.Test
+}
+
 // Possible values for CommandStatus
 const (
 	StatusPass    CommandStatus = "pass"

src/events/tcr_event_test.go

@@ -54,3 +54,9 @@ func Test_yaml_conversion_on_sample_tcr_event(t *testing.T) {
 	assert.Equal(t, expected, yaml)
 	assert.Equal(t, *event, FromYAML(yaml))
 }
+
+func Test_ChangedLines_can_sum_its_total_line_changes(t *testing.T) {
+	changedLines := ChangedLines{1, 2}
+
+	assert.Equal(t, 1+2, changedLines.All())
+}

src/events/tcr_events.go

@@ -193,12 +193,35 @@ func (events *TcrEvents) TestLineChangesPerCommit() IntAggregates {
 // AllLineChangesPerCommit returns the minimum, average and maximum number of changed
 // lines per commit (source and tests)
 func (events *TcrEvents) AllLineChangesPerCommit() IntAggregates {
-	return events.lineChangesPerCommit(
-		func(e DatedTcrEvent) int {
-			return e.Event.Changes.Src + e.Event.Changes.Test
-		})
+	return events.lineChangesPerCommit(allLineChanges)
+}
+
+// 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)
+	return passingEvents.lineChangesPerCommit(allLineChanges)
+}
+
+func allLineChanges(e DatedTcrEvent) int {
+	return e.Event.Changes.All()
+}
+
+func eventsWithGreenStatus(events *TcrEvents) TcrEvents {
+	return filter(*events, func(event DatedTcrEvent) bool {
+		return event.Event.Status == StatusPass
+	})
 }
 
+func filter[T any](slice []T, f func(T) bool) []T {
+	var n []T
+	for _, e := range slice {
+		if f(e) {
+			n = append(n, e)
+		}
+	}
+	return n
+}
 func (events *TcrEvents) lineChangesPerCommit(metricFunc func(e DatedTcrEvent) int) IntAggregates {
 	if len(*events) == 0 {
 		return IntAggregates{0, 0, 0}

src/events/tcr_events_test.go

@@ -442,6 +442,49 @@ 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
+	}{
+		{
+			"1 passing event",
+			TcrEvents{*ADatedTcrEvent(WithTcrEvent(*ATcrEvent(
+				WithCommandStatus(StatusPass),
+				WithModifiedSrcLines(3),
+				WithModifiedTestLines(0))))},
+			IntAggregates{min: 3, avg: 3, max: 3},
+		},
+		{
+			"summing all tests and source line changes",
+			TcrEvents{*ADatedTcrEvent(WithTcrEvent(*ATcrEvent(
+				WithCommandStatus(StatusPass),
+				WithModifiedSrcLines(3),
+				WithModifiedTestLines(2))))},
+			IntAggregates{min: 5, avg: 5, max: 5},
+		},
+		{
+			"1 passing and 1 failing event",
+			TcrEvents{
+				*ADatedTcrEvent(WithTcrEvent(*ATcrEvent(
+					WithCommandStatus(StatusPass),
+					WithModifiedSrcLines(4),
+					WithModifiedTestLines(0)))),
+				*ADatedTcrEvent(WithTcrEvent(*ATcrEvent(
+					WithCommandStatus(StatusFail),
+					WithModifiedSrcLines(5),
+					WithModifiedTestLines(0))))},
+			IntAggregates{min: 4, avg: 4, max: 4},
+		},
+	}
+	for _, tt := range testFlags {
+		t.Run(tt.desc, func(t *testing.T) {
+			assert.Equal(t, tt.expected, tt.events.AllLineChangesPerGreenCommit())
+		})
+	}
+}
+
 func Test_events_line_changes_per_commit(t *testing.T) {
 	testFlags := []struct {
 		desc         string