feat: preview task canvases with workspace data (#3887)

apps/backend/internal/canvas/scope_metrics_test.go

@@ -0,0 +1,42 @@
+package canvas
+
+import (
+	"expvar"
+	"strconv"
+	"testing"
+)
+
+func canvasScopeMetricCount(t *testing.T, label string) int64 {
+	t.Helper()
+	value := expvar.Get("canvas_data_scope_transition_total")
+	if value == nil {
+		t.Fatal("canvas data-scope transition counter is not registered")
+	}
+	metrics, ok := value.(*expvar.Map)
+	if !ok {
+		t.Fatalf("canvas data-scope transition metric has type %T, want *expvar.Map", value)
+	}
+	var count int64
+	metrics.Do(func(keyValue expvar.KeyValue) {
+		if keyValue.Key != label {
+			return
+		}
+		parsed, err := strconv.ParseInt(keyValue.Value.String(), 10, 64)
+		if err != nil {
+			t.Errorf("canvas data-scope metric %q value = %q: %v", label, keyValue.Value.String(), err)
+			return
+		}
+		count = parsed
+	})
+	return count
+}
+
+func TestRecordCanvasScopeTransitionUsesFixedLabels(t *testing.T) {
+	label := "transition=reviewed_upgrade;result=data_scope_enabled"
+	before := canvasScopeMetricCount(t, label)
+	recordCanvasScopeTransition(canvasScopeReviewedUpgrade, canvasScopeEnabled)
+	after := canvasScopeMetricCount(t, label)
+	if after-before != 1 {
+		t.Fatalf("transition counter delta = %d, want 1", after-before)
+	}
+}