1 files changed, 297 insertions, 0 deletions
diff --git a/src/context/context_test.go b/src/context/context_test.go
new file mode 100644
index 0000000..57066c9
--- /dev/null
+++ b/src/context/context_test.go
@@ -0,0 +1,297 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package context
+
+// Tests in package context cannot depend directly on package testing due to an import cycle.
+// If your test does requires access to unexported members of the context package,
+// add your test below as `func XTestFoo(t testingT)` and add a `TestFoo` to x_test.go
+// that calls it. Otherwise, write a regular test in a test.go file in package context_test.
+
+import (
+	"time"
+)
+
+type testingT interface {
+	Deadline() (time.Time, bool)
+	Error(args ...any)
+	Errorf(format string, args ...any)
+	Fail()
+	FailNow()
+	Failed() bool
+	Fatal(args ...any)
+	Fatalf(format string, args ...any)
+	Helper()
+	Log(args ...any)
+	Logf(format string, args ...any)
+	Name() string
+	Parallel()
+	Skip(args ...any)
+	SkipNow()
+	Skipf(format string, args ...any)
+	Skipped() bool
+}
+
+const veryLongDuration = 1000 * time.Hour // an arbitrary upper bound on the test's running time
+
+func contains(m map[canceler]struct{}, key canceler) bool {
+	_, ret := m[key]
+	return ret
+}
+
+func XTestParentFinishesChild(t testingT) {
+	// Context tree:
+	// parent -> cancelChild
+	// parent -> valueChild -> timerChild
+	// parent -> afterChild
+	parent, cancel := WithCancel(Background())
+	cancelChild, stop := WithCancel(parent)
+	defer stop()
+	valueChild := WithValue(parent, "key", "value")
+	timerChild, stop := WithTimeout(valueChild, veryLongDuration)
+	defer stop()
+	afterStop := AfterFunc(parent, func() {})
+	defer afterStop()
+
+	select {
+	case x := <-parent.Done():
+		t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+	case x := <-cancelChild.Done():
+		t.Errorf("<-cancelChild.Done() == %v want nothing (it should block)", x)
+	case x := <-timerChild.Done():
+		t.Errorf("<-timerChild.Done() == %v want nothing (it should block)", x)
+	case x := <-valueChild.Done():
+		t.Errorf("<-valueChild.Done() == %v want nothing (it should block)", x)
+	default:
+	}
+
+	// The parent's children should contain the three cancelable children.
+	pc := parent.(*cancelCtx)
+	cc := cancelChild.(*cancelCtx)
+	tc := timerChild.(*timerCtx)
+	pc.mu.Lock()
+	var ac *afterFuncCtx
+	for c := range pc.children {
+		if a, ok := c.(*afterFuncCtx); ok {
+			ac = a
+			break
+		}
+	}
+	if len(pc.children) != 3 || !contains(pc.children, cc) || !contains(pc.children, tc) || ac == nil {
+		t.Errorf("bad linkage: pc.children = %v, want %v, %v, and an afterFunc",
+			pc.children, cc, tc)
+	}
+	pc.mu.Unlock()
+
+	if p, ok := parentCancelCtx(cc.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(cancelChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+	if p, ok := parentCancelCtx(tc.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(timerChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+	if p, ok := parentCancelCtx(ac.Context); !ok || p != pc {
+		t.Errorf("bad linkage: parentCancelCtx(afterChild.Context) = %v, %v want %v, true", p, ok, pc)
+	}
+
+	cancel()
+
+	pc.mu.Lock()
+	if len(pc.children) != 0 {
+		t.Errorf("pc.cancel didn't clear pc.children = %v", pc.children)
+	}
+	pc.mu.Unlock()
+
+	// parent and children should all be finished.
+	check := func(ctx Context, name string) {
+		select {
+		case <-ctx.Done():
+		default:
+			t.Errorf("<-%s.Done() blocked, but shouldn't have", name)
+		}
+		if e := ctx.Err(); e != Canceled {
+			t.Errorf("%s.Err() == %v want %v", name, e, Canceled)
+		}
+	}
+	check(parent, "parent")
+	check(cancelChild, "cancelChild")
+	check(valueChild, "valueChild")
+	check(timerChild, "timerChild")
+
+	// WithCancel should return a canceled context on a canceled parent.
+	precanceledChild := WithValue(parent, "key", "value")
+	select {
+	case <-precanceledChild.Done():
+	default:
+		t.Errorf("<-precanceledChild.Done() blocked, but shouldn't have")
+	}
+	if e := precanceledChild.Err(); e != Canceled {
+		t.Errorf("precanceledChild.Err() == %v want %v", e, Canceled)
+	}
+}
+
+func XTestChildFinishesFirst(t testingT) {
+	cancelable, stop := WithCancel(Background())
+	defer stop()
+	for _, parent := range []Context{Background(), cancelable} {
+		child, cancel := WithCancel(parent)
+
+		select {
+		case x := <-parent.Done():
+			t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+		case x := <-child.Done():
+			t.Errorf("<-child.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+
+		cc := child.(*cancelCtx)
+		pc, pcok := parent.(*cancelCtx) // pcok == false when parent == Background()
+		if p, ok := parentCancelCtx(cc.Context); ok != pcok || (ok && pc != p) {
+			t.Errorf("bad linkage: parentCancelCtx(cc.Context) = %v, %v want %v, %v", p, ok, pc, pcok)
+		}
+
+		if pcok {
+			pc.mu.Lock()
+			if len(pc.children) != 1 || !contains(pc.children, cc) {
+				t.Errorf("bad linkage: pc.children = %v, cc = %v", pc.children, cc)
+			}
+			pc.mu.Unlock()
+		}
+
+		cancel()
+
+		if pcok {
+			pc.mu.Lock()
+			if len(pc.children) != 0 {
+				t.Errorf("child's cancel didn't remove self from pc.children = %v", pc.children)
+			}
+			pc.mu.Unlock()
+		}
+
+		// child should be finished.
+		select {
+		case <-child.Done():
+		default:
+			t.Errorf("<-child.Done() blocked, but shouldn't have")
+		}
+		if e := child.Err(); e != Canceled {
+			t.Errorf("child.Err() == %v want %v", e, Canceled)
+		}
+
+		// parent should not be finished.
+		select {
+		case x := <-parent.Done():
+			t.Errorf("<-parent.Done() == %v want nothing (it should block)", x)
+		default:
+		}
+		if e := parent.Err(); e != nil {
+			t.Errorf("parent.Err() == %v want nil", e)
+		}
+	}
+}
+
+func XTestCancelRemoves(t testingT) {
+	checkChildren := func(when string, ctx Context, want int) {
+		if got := len(ctx.(*cancelCtx).children); got != want {
+			t.Errorf("%s: context has %d children, want %d", when, got, want)
+		}
+	}
+
+	ctx, _ := WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	_, cancel := WithCancel(ctx)
+	checkChildren("with WithCancel child ", ctx, 1)
+	cancel()
+	checkChildren("after canceling WithCancel child", ctx, 0)
+
+	ctx, _ = WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	_, cancel = WithTimeout(ctx, 60*time.Minute)
+	checkChildren("with WithTimeout child ", ctx, 1)
+	cancel()
+	checkChildren("after canceling WithTimeout child", ctx, 0)
+
+	ctx, _ = WithCancel(Background())
+	checkChildren("after creation", ctx, 0)
+	stop := AfterFunc(ctx, func() {})
+	checkChildren("with AfterFunc child ", ctx, 1)
+	stop()
+	checkChildren("after stopping AfterFunc child ", ctx, 0)
+}
+
+type myCtx struct {
+	Context
+}
+
+type myDoneCtx struct {
+	Context
+}
+
+func (d *myDoneCtx) Done() <-chan struct{} {
+	c := make(chan struct{})
+	return c
+}
+func XTestCustomContextGoroutines(t testingT) {
+	g := goroutines.Load()
+	checkNoGoroutine := func() {
+		t.Helper()
+		now := goroutines.Load()
+		if now != g {
+			t.Fatalf("%d goroutines created", now-g)
+		}
+	}
+	checkCreatedGoroutine := func() {
+		t.Helper()
+		now := goroutines.Load()
+		if now != g+1 {
+			t.Fatalf("%d goroutines created, want 1", now-g)
+		}
+		g = now
+	}
+
+	_, cancel0 := WithCancel(&myDoneCtx{Background()})
+	cancel0()
+	checkCreatedGoroutine()
+
+	_, cancel0 = WithTimeout(&myDoneCtx{Background()}, veryLongDuration)
+	cancel0()
+	checkCreatedGoroutine()
+
+	checkNoGoroutine()
+	defer checkNoGoroutine()
+
+	ctx1, cancel1 := WithCancel(Background())
+	defer cancel1()
+	checkNoGoroutine()
+
+	ctx2 := &myCtx{ctx1}
+	ctx3, cancel3 := WithCancel(ctx2)
+	defer cancel3()
+	checkNoGoroutine()
+
+	_, cancel3b := WithCancel(&myDoneCtx{ctx2})
+	defer cancel3b()
+	checkCreatedGoroutine() // ctx1 is not providing Done, must not be used
+
+	ctx4, cancel4 := WithTimeout(ctx3, veryLongDuration)
+	defer cancel4()
+	checkNoGoroutine()
+
+	ctx5, cancel5 := WithCancel(ctx4)
+	defer cancel5()
+	checkNoGoroutine()
+
+	cancel5()
+	checkNoGoroutine()
+
+	_, cancel6 := WithTimeout(ctx5, veryLongDuration)
+	defer cancel6()
+	checkNoGoroutine()
+
+	// Check applied to canceled context.
+	cancel6()
+	cancel1()
+	_, cancel7 := WithCancel(ctx5)
+	defer cancel7()
+	checkNoGoroutine()
+}