test(observer,profiler): add comprehensive tests with 79.3% coverage

- Add 13 observer tests: openSpan, closeSpan, withProfiler/Tracer, integration
- Add 6 profiler tests: span merge, subflow skip, concurrent safety

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: noneback

observer_test.go

@@ -0,0 +1,270 @@
+package gotaskflow
+
+import (
+	"bytes"
+	"sync"
+	"testing"
+	"time"
+)
+
+// TestObserverOpenSpan tests that openSpan creates a span with correct attributes.
+func TestObserverOpenSpan(t *testing.T) {
+	obs := newObserver()
+	obs.withProfiler(newProfiler())
+
+	node := &innerNode{
+		name:       "test-task",
+		Typ:        nodeStatic,
+		dependents: []*innerNode{{name: "dep1"}, {name: "dep2"}},
+	}
+
+	s := obs.openSpan(node, nil)
+	if s == nil {
+		t.Fatal("expected non-nil span")
+	}
+	if s.extra.name != "test-task" {
+		t.Errorf("expected name 'test-task', got %q", s.extra.name)
+	}
+	if s.extra.typ != nodeStatic {
+		t.Errorf("expected type nodeStatic, got %q", s.extra.typ)
+	}
+	if s.parent != nil {
+		t.Errorf("expected nil parent, got %v", s.parent)
+	}
+	if len(s.dependents) != 2 || s.dependents[0] != "dep1" || s.dependents[1] != "dep2" {
+		t.Errorf("expected dependents [dep1, dep2], got %v", s.dependents)
+	}
+}
+
+// TestObserverOpenSpanNil tests that openSpan returns nil when no profiler or tracer is set.
+func TestObserverOpenSpanNil(t *testing.T) {
+	obs := newObserver()
+
+	node := &innerNode{
+		name: "test-task",
+		Typ:  nodeStatic,
+	}
+
+	s := obs.openSpan(node, nil)
+	if s != nil {
+		t.Errorf("expected nil span when no profiler/tracer, got %v", s)
+	}
+}
+
+// TestObserverCloseSpan tests that closeSpan records the span to profiler.
+func TestObserverCloseSpan(t *testing.T) {
+	obs := newObserver()
+	p := newProfiler()
+	obs.withProfiler(p)
+
+	node := &innerNode{
+		name: "test-task",
+		Typ:  nodeStatic,
+	}
+
+	s := obs.openSpan(node, nil)
+	time.Sleep(1 * time.Millisecond) // ensure some duration
+	obs.closeSpan(s, true)
+
+	if len(p.spans) != 1 {
+		t.Errorf("expected 1 span in profiler, got %d", len(p.spans))
+	}
+	if s.cost <= 0 {
+		t.Errorf("expected positive cost, got %v", s.cost)
+	}
+}
+
+// TestObserverCloseSpanNotOk tests that closeSpan does not record span when ok=false (panic).
+func TestObserverCloseSpanNotOk(t *testing.T) {
+	obs := newObserver()
+	p := newProfiler()
+	obs.withProfiler(p)
+
+	node := &innerNode{
+		name: "test-task",
+		Typ:  nodeStatic,
+	}
+
+	s := obs.openSpan(node, nil)
+	time.Sleep(1 * time.Millisecond)
+	obs.closeSpan(s, false) // ok=false means panic occurred
+
+	if len(p.spans) != 0 {
+		t.Errorf("expected 0 spans in profiler (panicked task), got %d", len(p.spans))
+	}
+}
+
+// TestObserverCloseSpanNil tests that closeSpan handles nil span gracefully.
+func TestObserverCloseSpanNil(t *testing.T) {
+	obs := newObserver()
+	obs.withProfiler(newProfiler())
+
+	// Should not panic
+	obs.closeSpan(nil, true)
+}
+
+// TestObserverWithProfiler tests that withProfiler sets the profiler correctly.
+func TestObserverWithProfiler(t *testing.T) {
+	obs := newObserver()
+	if obs.profiler != nil {
+		t.Error("expected nil profiler initially")
+	}
+
+	p := newProfiler()
+	obs.withProfiler(p)
+	if obs.profiler != p {
+		t.Error("profiler not set correctly")
+	}
+}
+
+// TestObserverWithTracer tests that withTracer sets the tracer correctly.
+func TestObserverWithTracer(t *testing.T) {
+	obs := newObserver()
+	if obs.tracer != nil {
+		t.Error("expected nil tracer initially")
+	}
+
+	tr := newTracer()
+	obs.withTracer(tr)
+	if obs.tracer != tr {
+		t.Error("tracer not set correctly")
+	}
+}
+
+// TestObserverSpanParentChain tests that span parent chain is preserved.
+func TestObserverSpanParentChain(t *testing.T) {
+	obs := newObserver()
+	obs.withProfiler(newProfiler())
+
+	parentNode := &innerNode{name: "parent", Typ: nodeStatic}
+	childNode := &innerNode{name: "child", Typ: nodeStatic}
+
+	parentSpan := obs.openSpan(parentNode, nil)
+	childSpan := obs.openSpan(childNode, parentSpan)
+
+	if childSpan.parent != parentSpan {
+		t.Error("child span should have parent span set")
+	}
+	if parentSpan.parent != nil {
+		t.Error("parent span should have nil parent")
+	}
+}
+
+// TestObserverWithBothProfilerAndTracer tests that both profiler and tracer work together.
+func TestObserverWithBothProfilerAndTracer(t *testing.T) {
+	obs := newObserver()
+	p := newProfiler()
+	tr := newTracer()
+	obs.withProfiler(p)
+	obs.withTracer(tr)
+
+	node := &innerNode{name: "test-task", Typ: nodeStatic}
+	s := obs.openSpan(node, nil)
+	time.Sleep(1 * time.Millisecond)
+	obs.closeSpan(s, true)
+
+	if len(p.spans) != 1 {
+		t.Errorf("expected 1 span in profiler, got %d", len(p.spans))
+	}
+	if len(tr.events) != 1 {
+		t.Errorf("expected 1 event in tracer, got %d", len(tr.events))
+	}
+}
+
+// TestObserverConcurrent tests concurrent use of observer.
+func TestObserverConcurrent(t *testing.T) {
+	obs := newObserver()
+	p := newProfiler()
+	tr := newTracer()
+	obs.withProfiler(p)
+	obs.withTracer(tr)
+
+	var wg sync.WaitGroup
+	n := 100
+	wg.Add(n)
+
+	for i := 0; i < n; i++ {
+		go func(i int) {
+			defer wg.Done()
+			node := &innerNode{
+				name: "task",
+				Typ:  nodeStatic,
+			}
+			s := obs.openSpan(node, nil)
+			time.Sleep(time.Microsecond)
+			obs.closeSpan(s, true)
+		}(i)
+	}
+	wg.Wait()
+
+	// Note: profiler merges by attr, so may have fewer than n spans
+	// But tracer should have all n events
+	if len(tr.events) != n {
+		t.Errorf("expected %d tracer events, got %d", n, len(tr.events))
+	}
+}
+
+// TestObserverIntegrationWithExecutor tests observer works correctly with executor.
+func TestObserverIntegrationWithExecutor(t *testing.T) {
+	tf := NewTaskFlow("test-flow")
+	a := tf.NewTask("A", func() {})
+	b := tf.NewTask("B", func() {})
+	a.Precede(b)
+
+	exec := NewExecutor(4, WithProfiler())
+	exec.Run(tf).Wait()
+
+	var buf bytes.Buffer
+	err := exec.Profile(&buf)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if buf.Len() == 0 {
+		t.Error("expected profile output, got empty")
+	}
+}
+
+// TestObserverIntegrationWithTracer tests observer works correctly with tracer.
+func TestObserverIntegrationWithTracer(t *testing.T) {
+	tf := NewTaskFlow("test-flow")
+	a := tf.NewTask("A", func() {})
+	b := tf.NewTask("B", func() {})
+	a.Precede(b)
+
+	exec := NewExecutor(4, WithTracer())
+	exec.Run(tf).Wait()
+
+	var buf bytes.Buffer
+	err := exec.Trace(&buf)
+	if err != nil {
+		t.Errorf("unexpected error: %v", err)
+	}
+	if buf.Len() == 0 {
+		t.Error("expected trace output, got empty")
+	}
+}
+
+// TestObserverIntegrationWithBoth tests observer with both profiler and tracer.
+func TestObserverIntegrationWithBoth(t *testing.T) {
+	tf := NewTaskFlow("test-flow")
+	a := tf.NewTask("A", func() {})
+	b := tf.NewTask("B", func() {})
+	a.Precede(b)
+
+	exec := NewExecutor(4, WithProfiler(), WithTracer())
+	exec.Run(tf).Wait()
+
+	var profileBuf, traceBuf bytes.Buffer
+	if err := exec.Profile(&profileBuf); err != nil {
+		t.Errorf("unexpected profile error: %v", err)
+	}
+	if err := exec.Trace(&traceBuf); err != nil {
+		t.Errorf("unexpected trace error: %v", err)
+	}
+	if profileBuf.Len() == 0 {
+		t.Error("expected profile output")
+	}
+	if traceBuf.Len() == 0 {
+		t.Error("expected trace output")
+	}
+}