parser/gotest: Implement active id tracking in output collector

parser/gotest/internal/collector/collector.go

@@ -14,10 +14,14 @@ type line struct {
 }
 
 // Output stores output lines grouped by id. Output can be retrieved for one or
-// more ids and output of different ids can be merged together, all while
-// preserving their original order based on the time it was collected.
+// more ids and output for different ids can be merged together, while
+// preserving their insertion original order based on the time it was
+// collected.
+// Output also tracks the active id, so you can append output without providing
+// an id.
 type Output struct {
-	m map[int][]line
+	m  map[int][]line
+	id int // active id
 }
 
 // New returns a new output collector.
@@ -27,11 +31,17 @@ func New() *Output {
 
 // Clear deletes all output for the given id.
 func (o *Output) Clear(id int) {
-	o.m[id] = nil
+	delete(o.m, id)
 }
 
-// Append appends the given line of text to the output of the specified id.
-func (o *Output) Append(id int, text string) {
+// Append appends the given line of text to the output of the currently active
+// id.
+func (o *Output) Append(text string) {
+	o.m[o.id] = append(o.m[o.id], line{time.Now(), text})
+}
+
+// AppendToID appends the given line of text to the output of the given id.
+func (o *Output) AppendToID(id int, text string) {
 	o.m[id] = append(o.m[id], line{time.Now(), text})
 }
 
@@ -79,3 +89,9 @@ func (o *Output) Merge(fromID, intoID int) {
 	o.m[intoID] = merged
 	delete(o.m, fromID)
 }
+
+// SetActiveID sets the active id. Text appended to this output will be
+// associated with the active id.
+func (o *Output) SetActiveID(id int) {
+	o.id = id
+}

parser/gotest/internal/collector/collector_test.go

@@ -9,8 +9,8 @@ import (
 
 func TestClear(t *testing.T) {
 	o := New()
-	o.Append(1, "1")
-	o.Append(2, "2")
+	o.AppendToID(1, "1")
+	o.AppendToID(2, "2")
 	o.Clear(1)
 
 	want := []string(nil)
@@ -28,22 +28,22 @@ func TestClear(t *testing.T) {
 
 func TestAppendAndGet(t *testing.T) {
 	o := New()
-	o.Append(1, "1.1")
-	o.Append(1, "1.2")
-	o.Append(2, "2")
-	o.Append(1, "1.3")
+	o.AppendToID(1, "1.1")
+	o.AppendToID(1, "1.2")
+	o.AppendToID(2, "2")
+	o.AppendToID(1, "1.3")
 
 	want := []string{"1.1", "1.2", "1.3"}
 	got := o.Get(1)
 	if diff := cmp.Diff(want, got); diff != "" {
-		t.Errorf("Append() incorrect (-want +got):\n%s", diff)
+		t.Errorf("AppendToID() incorrect (-want +got):\n%s", diff)
 	}
 }
 
 func TestContains(t *testing.T) {
 	o := New()
-	o.Append(1, "1")
-	o.Append(2, "2")
+	o.AppendToID(1, "1")
+	o.AppendToID(2, "2")
 	o.Clear(1)
 
 	if !o.Contains(2) {
@@ -59,7 +59,7 @@ func TestContains(t *testing.T) {
 func TestGetAll(t *testing.T) {
 	o := New()
 	for i := 1; i <= 10; i++ {
-		o.Append(i%3, strconv.Itoa(i))
+		o.AppendToID(i%3, strconv.Itoa(i))
 	}
 
 	want := []string{"1", "2", "4", "5", "7", "8", "10"}
@@ -72,7 +72,7 @@ func TestGetAll(t *testing.T) {
 func TestMerge(t *testing.T) {
 	o := New()
 	for i := 1; i <= 10; i++ {
-		o.Append(i%3, strconv.Itoa(i))
+		o.AppendToID(i%3, strconv.Itoa(i))
 	}
 
 	o.Merge(2, 1)
@@ -89,3 +89,29 @@ func TestMerge(t *testing.T) {
 		t.Errorf("Get(2) after Merge(2, 1) incorrect (-want +got):\n%s", diff)
 	}
 }
+
+func TestActiveID(t *testing.T) {
+	o := New()
+
+	o.Append("0")
+	o.SetActiveID(2)
+	o.Append("2")
+	o.SetActiveID(1)
+	o.Append("1")
+	o.SetActiveID(0)
+	o.Append("0")
+
+	expected := [][]string{
+		{"0", "0"},
+		{"1"},
+		{"2"},
+	}
+	for i := 0; i < 2; i++ {
+		want := expected[i]
+		got := o.Get(i)
+		if diff := cmp.Diff(want, got); diff != "" {
+			t.Errorf("Get(0) after SetActiveID incorrect (-want +got):\n%s", diff)
+		}
+	}
+
+}