Adding upstream version 1.22.1.upstream/1.22.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 992 insertions, 0 deletions

diff --git a/src/testing/sub_test.go b/src/testing/sub_test.go
new file mode 100644
index 0000000..1c23d05
--- /dev/null
+++ b/src/testing/sub_test.go
@@ -0,0 +1,992 @@
+// Copyright 2016 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 testing
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"regexp"
+	"runtime"
+	"strings"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+func init() {
+	// Make benchmark tests run 10x faster.
+	benchTime.d = 100 * time.Millisecond
+}
+
+func TestTestContext(t *T) {
+	const (
+		add1 = 0
+		done = 1
+	)
+	// After each of the calls are applied to the context, the
+	type call struct {
+		typ int // run or done
+		// result from applying the call
+		running int
+		waiting int
+		started bool
+	}
+	testCases := []struct {
+		max int
+		run []call
+	}{{
+		max: 1,
+		run: []call{
+			{typ: add1, running: 1, waiting: 0, started: true},
+			{typ: done, running: 0, waiting: 0, started: false},
+		},
+	}, {
+		max: 1,
+		run: []call{
+			{typ: add1, running: 1, waiting: 0, started: true},
+			{typ: add1, running: 1, waiting: 1, started: false},
+			{typ: done, running: 1, waiting: 0, started: true},
+			{typ: done, running: 0, waiting: 0, started: false},
+			{typ: add1, running: 1, waiting: 0, started: true},
+		},
+	}, {
+		max: 3,
+		run: []call{
+			{typ: add1, running: 1, waiting: 0, started: true},
+			{typ: add1, running: 2, waiting: 0, started: true},
+			{typ: add1, running: 3, waiting: 0, started: true},
+			{typ: add1, running: 3, waiting: 1, started: false},
+			{typ: add1, running: 3, waiting: 2, started: false},
+			{typ: add1, running: 3, waiting: 3, started: false},
+			{typ: done, running: 3, waiting: 2, started: true},
+			{typ: add1, running: 3, waiting: 3, started: false},
+			{typ: done, running: 3, waiting: 2, started: true},
+			{typ: done, running: 3, waiting: 1, started: true},
+			{typ: done, running: 3, waiting: 0, started: true},
+			{typ: done, running: 2, waiting: 0, started: false},
+			{typ: done, running: 1, waiting: 0, started: false},
+			{typ: done, running: 0, waiting: 0, started: false},
+		},
+	}}
+	for i, tc := range testCases {
+		ctx := &testContext{
+			startParallel: make(chan bool),
+			maxParallel:   tc.max,
+		}
+		for j, call := range tc.run {
+			doCall := func(f func()) chan bool {
+				done := make(chan bool)
+				go func() {
+					f()
+					done <- true
+				}()
+				return done
+			}
+			started := false
+			switch call.typ {
+			case add1:
+				signal := doCall(ctx.waitParallel)
+				select {
+				case <-signal:
+					started = true
+				case ctx.startParallel <- true:
+					<-signal
+				}
+			case done:
+				signal := doCall(ctx.release)
+				select {
+				case <-signal:
+				case <-ctx.startParallel:
+					started = true
+					<-signal
+				}
+			}
+			if started != call.started {
+				t.Errorf("%d:%d:started: got %v; want %v", i, j, started, call.started)
+			}
+			if ctx.running != call.running {
+				t.Errorf("%d:%d:running: got %v; want %v", i, j, ctx.running, call.running)
+			}
+			if ctx.numWaiting != call.waiting {
+				t.Errorf("%d:%d:waiting: got %v; want %v", i, j, ctx.numWaiting, call.waiting)
+			}
+		}
+	}
+}
+
+func TestTRun(t *T) {
+	realTest := t
+	testCases := []struct {
+		desc   string
+		ok     bool
+		maxPar int
+		chatty bool
+		json   bool
+		output string
+		f      func(*T)
+	}{{
+		desc:   "failnow skips future sequential and parallel tests at same level",
+		ok:     false,
+		maxPar: 1,
+		output: `
+--- FAIL: failnow skips future sequential and parallel tests at same level (N.NNs)
+    --- FAIL: failnow skips future sequential and parallel tests at same level/#00 (N.NNs)
+    `,
+		f: func(t *T) {
+			ranSeq := false
+			ranPar := false
+			t.Run("", func(t *T) {
+				t.Run("par", func(t *T) {
+					t.Parallel()
+					ranPar = true
+				})
+				t.Run("seq", func(t *T) {
+					ranSeq = true
+				})
+				t.FailNow()
+				t.Run("seq", func(t *T) {
+					realTest.Error("test must be skipped")
+				})
+				t.Run("par", func(t *T) {
+					t.Parallel()
+					realTest.Error("test must be skipped.")
+				})
+			})
+			if !ranPar {
+				realTest.Error("parallel test was not run")
+			}
+			if !ranSeq {
+				realTest.Error("sequential test was not run")
+			}
+		},
+	}, {
+		desc:   "failure in parallel test propagates upwards",
+		ok:     false,
+		maxPar: 1,
+		output: `
+--- FAIL: failure in parallel test propagates upwards (N.NNs)
+    --- FAIL: failure in parallel test propagates upwards/#00 (N.NNs)
+        --- FAIL: failure in parallel test propagates upwards/#00/par (N.NNs)
+        `,
+		f: func(t *T) {
+			t.Run("", func(t *T) {
+				t.Parallel()
+				t.Run("par", func(t *T) {
+					t.Parallel()
+					t.Fail()
+				})
+			})
+		},
+	}, {
+		desc:   "skipping without message, chatty",
+		ok:     true,
+		chatty: true,
+		output: `
+=== RUN   skipping without message, chatty
+--- SKIP: skipping without message, chatty (N.NNs)`,
+		f: func(t *T) { t.SkipNow() },
+	}, {
+		desc:   "chatty with recursion",
+		ok:     true,
+		chatty: true,
+		output: `
+=== RUN   chatty with recursion
+=== RUN   chatty with recursion/#00
+=== RUN   chatty with recursion/#00/#00
+--- PASS: chatty with recursion (N.NNs)
+    --- PASS: chatty with recursion/#00 (N.NNs)
+        --- PASS: chatty with recursion/#00/#00 (N.NNs)`,
+		f: func(t *T) {
+			t.Run("", func(t *T) {
+				t.Run("", func(t *T) {})
+			})
+		},
+	}, {
+		desc:   "chatty with recursion and json",
+		ok:     false,
+		chatty: true,
+		json:   true,
+		output: `
+^V=== RUN   chatty with recursion and json
+^V=== RUN   chatty with recursion and json/#00
+^V=== RUN   chatty with recursion and json/#00/#00
+^V--- PASS: chatty with recursion and json/#00/#00 (N.NNs)
+^V=== NAME  chatty with recursion and json/#00
+^V=== RUN   chatty with recursion and json/#00/#01
+    sub_test.go:NNN: skip
+^V--- SKIP: chatty with recursion and json/#00/#01 (N.NNs)
+^V=== NAME  chatty with recursion and json/#00
+^V=== RUN   chatty with recursion and json/#00/#02
+    sub_test.go:NNN: fail
+^V--- FAIL: chatty with recursion and json/#00/#02 (N.NNs)
+^V=== NAME  chatty with recursion and json/#00
+^V--- FAIL: chatty with recursion and json/#00 (N.NNs)
+^V=== NAME  chatty with recursion and json
+^V--- FAIL: chatty with recursion and json (N.NNs)
+^V=== NAME  `,
+		f: func(t *T) {
+			t.Run("", func(t *T) {
+				t.Run("", func(t *T) {})
+				t.Run("", func(t *T) { t.Skip("skip") })
+				t.Run("", func(t *T) { t.Fatal("fail") })
+			})
+		},
+	}, {
+		desc: "skipping without message, not chatty",
+		ok:   true,
+		f:    func(t *T) { t.SkipNow() },
+	}, {
+		desc: "skipping after error",
+		output: `
+--- FAIL: skipping after error (N.NNs)
+    sub_test.go:NNN: an error
+    sub_test.go:NNN: skipped`,
+		f: func(t *T) {
+			t.Error("an error")
+			t.Skip("skipped")
+		},
+	}, {
+		desc:   "use Run to locally synchronize parallelism",
+		ok:     true,
+		maxPar: 1,
+		f: func(t *T) {
+			var count uint32
+			t.Run("waitGroup", func(t *T) {
+				for i := 0; i < 4; i++ {
+					t.Run("par", func(t *T) {
+						t.Parallel()
+						atomic.AddUint32(&count, 1)
+					})
+				}
+			})
+			if count != 4 {
+				t.Errorf("count was %d; want 4", count)
+			}
+		},
+	}, {
+		desc: "alternate sequential and parallel",
+		// Sequential tests should partake in the counting of running threads.
+		// Otherwise, if one runs parallel subtests in sequential tests that are
+		// itself subtests of parallel tests, the counts can get askew.
+		ok:     true,
+		maxPar: 1,
+		f: func(t *T) {
+			t.Run("a", func(t *T) {
+				t.Parallel()
+				t.Run("b", func(t *T) {
+					// Sequential: ensure running count is decremented.
+					t.Run("c", func(t *T) {
+						t.Parallel()
+					})
+
+				})
+			})
+		},
+	}, {
+		desc: "alternate sequential and parallel 2",
+		// Sequential tests should partake in the counting of running threads.
+		// Otherwise, if one runs parallel subtests in sequential tests that are
+		// itself subtests of parallel tests, the counts can get askew.
+		ok:     true,
+		maxPar: 2,
+		f: func(t *T) {
+			for i := 0; i < 2; i++ {
+				t.Run("a", func(t *T) {
+					t.Parallel()
+					time.Sleep(time.Nanosecond)
+					for i := 0; i < 2; i++ {
+						t.Run("b", func(t *T) {
+							time.Sleep(time.Nanosecond)
+							for i := 0; i < 2; i++ {
+								t.Run("c", func(t *T) {
+									t.Parallel()
+									time.Sleep(time.Nanosecond)
+								})
+							}
+
+						})
+					}
+				})
+			}
+		},
+	}, {
+		desc:   "stress test",
+		ok:     true,
+		maxPar: 4,
+		f: func(t *T) {
+			t.Parallel()
+			for i := 0; i < 12; i++ {
+				t.Run("a", func(t *T) {
+					t.Parallel()
+					time.Sleep(time.Nanosecond)
+					for i := 0; i < 12; i++ {
+						t.Run("b", func(t *T) {
+							time.Sleep(time.Nanosecond)
+							for i := 0; i < 12; i++ {
+								t.Run("c", func(t *T) {
+									t.Parallel()
+									time.Sleep(time.Nanosecond)
+									t.Run("d1", func(t *T) {})
+									t.Run("d2", func(t *T) {})
+									t.Run("d3", func(t *T) {})
+									t.Run("d4", func(t *T) {})
+								})
+							}
+						})
+					}
+				})
+			}
+		},
+	}, {
+		desc:   "skip output",
+		ok:     true,
+		maxPar: 4,
+		f: func(t *T) {
+			t.Skip()
+		},
+	}, {
+		desc: "subtest calls error on parent",
+		ok:   false,
+		output: `
+--- FAIL: subtest calls error on parent (N.NNs)
+    sub_test.go:NNN: first this
+    sub_test.go:NNN: and now this!
+    sub_test.go:NNN: oh, and this too`,
+		maxPar: 1,
+		f: func(t *T) {
+			t.Errorf("first this")
+			outer := t
+			t.Run("", func(t *T) {
+				outer.Errorf("and now this!")
+			})
+			t.Errorf("oh, and this too")
+		},
+	}, {
+		desc: "subtest calls fatal on parent",
+		ok:   false,
+		output: `
+--- FAIL: subtest calls fatal on parent (N.NNs)
+    sub_test.go:NNN: first this
+    sub_test.go:NNN: and now this!
+    --- FAIL: subtest calls fatal on parent/#00 (N.NNs)
+        testing.go:NNN: test executed panic(nil) or runtime.Goexit: subtest may have called FailNow on a parent test`,
+		maxPar: 1,
+		f: func(t *T) {
+			outer := t
+			t.Errorf("first this")
+			t.Run("", func(t *T) {
+				outer.Fatalf("and now this!")
+			})
+			t.Errorf("Should not reach here.")
+		},
+	}, {
+		desc: "subtest calls error on ancestor",
+		ok:   false,
+		output: `
+--- FAIL: subtest calls error on ancestor (N.NNs)
+    sub_test.go:NNN: Report to ancestor
+    --- FAIL: subtest calls error on ancestor/#00 (N.NNs)
+        sub_test.go:NNN: Still do this
+    sub_test.go:NNN: Also do this`,
+		maxPar: 1,
+		f: func(t *T) {
+			outer := t
+			t.Run("", func(t *T) {
+				t.Run("", func(t *T) {
+					outer.Errorf("Report to ancestor")
+				})
+				t.Errorf("Still do this")
+			})
+			t.Errorf("Also do this")
+		},
+	}, {
+		desc: "subtest calls fatal on ancestor",
+		ok:   false,
+		output: `
+--- FAIL: subtest calls fatal on ancestor (N.NNs)
+    sub_test.go:NNN: Nope`,
+		maxPar: 1,
+		f: func(t *T) {
+			outer := t
+			t.Run("", func(t *T) {
+				for i := 0; i < 4; i++ {
+					t.Run("", func(t *T) {
+						outer.Fatalf("Nope")
+					})
+					t.Errorf("Don't do this")
+				}
+				t.Errorf("And neither do this")
+			})
+			t.Errorf("Nor this")
+		},
+	}, {
+		desc:   "panic on goroutine fail after test exit",
+		ok:     false,
+		maxPar: 4,
+		f: func(t *T) {
+			ch := make(chan bool)
+			t.Run("", func(t *T) {
+				go func() {
+					<-ch
+					defer func() {
+						if r := recover(); r == nil {
+							realTest.Errorf("expected panic")
+						}
+						ch <- true
+					}()
+					t.Errorf("failed after success")
+				}()
+			})
+			ch <- true
+			<-ch
+		},
+	}, {
+		desc: "log in finished sub test logs to parent",
+		ok:   false,
+		output: `
+		--- FAIL: log in finished sub test logs to parent (N.NNs)
+    sub_test.go:NNN: message2
+    sub_test.go:NNN: message1
+    sub_test.go:NNN: error`,
+		maxPar: 1,
+		f: func(t *T) {
+			ch := make(chan bool)
+			t.Run("sub", func(t2 *T) {
+				go func() {
+					<-ch
+					t2.Log("message1")
+					ch <- true
+				}()
+			})
+			t.Log("message2")
+			ch <- true
+			<-ch
+			t.Errorf("error")
+		},
+	}, {
+		// A chatty test should always log with fmt.Print, even if the
+		// parent test has completed.
+		desc:   "log in finished sub test with chatty",
+		ok:     false,
+		chatty: true,
+		output: `
+		--- FAIL: log in finished sub test with chatty (N.NNs)`,
+		maxPar: 1,
+		f: func(t *T) {
+			ch := make(chan bool)
+			t.Run("sub", func(t2 *T) {
+				go func() {
+					<-ch
+					t2.Log("message1")
+					ch <- true
+				}()
+			})
+			t.Log("message2")
+			ch <- true
+			<-ch
+			t.Errorf("error")
+		},
+	}, {
+		// If a subtest panics we should run cleanups.
+		desc:   "cleanup when subtest panics",
+		ok:     false,
+		chatty: false,
+		output: `
+--- FAIL: cleanup when subtest panics (N.NNs)
+    --- FAIL: cleanup when subtest panics/sub (N.NNs)
+    sub_test.go:NNN: running cleanup`,
+		f: func(t *T) {
+			t.Cleanup(func() { t.Log("running cleanup") })
+			t.Run("sub", func(t2 *T) {
+				t2.FailNow()
+			})
+		},
+	}}
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *T) {
+			ctx := newTestContext(tc.maxPar, allMatcher())
+			buf := &strings.Builder{}
+			root := &T{
+				common: common{
+					signal:  make(chan bool),
+					barrier: make(chan bool),
+					name:    "",
+					w:       buf,
+				},
+				context: ctx,
+			}
+			if tc.chatty {
+				root.chatty = newChattyPrinter(root.w)
+				root.chatty.json = tc.json
+			}
+			ok := root.Run(tc.desc, tc.f)
+			ctx.release()
+
+			if ok != tc.ok {
+				t.Errorf("%s:ok: got %v; want %v", tc.desc, ok, tc.ok)
+			}
+			if ok != !root.Failed() {
+				t.Errorf("%s:root failed: got %v; want %v", tc.desc, !ok, root.Failed())
+			}
+			if ctx.running != 0 || ctx.numWaiting != 0 {
+				t.Errorf("%s:running and waiting non-zero: got %d and %d", tc.desc, ctx.running, ctx.numWaiting)
+			}
+			got := strings.TrimSpace(buf.String())
+			want := strings.TrimSpace(tc.output)
+			re := makeRegexp(want)
+			if ok, err := regexp.MatchString(re, got); !ok || err != nil {
+				t.Errorf("%s:output:\ngot:\n%s\nwant:\n%s", tc.desc, got, want)
+			}
+		})
+	}
+}
+
+func TestBRun(t *T) {
+	work := func(b *B) {
+		for i := 0; i < b.N; i++ {
+			time.Sleep(time.Nanosecond)
+		}
+	}
+	testCases := []struct {
+		desc   string
+		failed bool
+		chatty bool
+		output string
+		f      func(*B)
+	}{{
+		desc: "simulate sequential run of subbenchmarks.",
+		f: func(b *B) {
+			b.Run("", func(b *B) { work(b) })
+			time1 := b.result.NsPerOp()
+			b.Run("", func(b *B) { work(b) })
+			time2 := b.result.NsPerOp()
+			if time1 >= time2 {
+				t.Errorf("no time spent in benchmark t1 >= t2 (%d >= %d)", time1, time2)
+			}
+		},
+	}, {
+		desc: "bytes set by all benchmarks",
+		f: func(b *B) {
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			if b.result.Bytes != 20 {
+				t.Errorf("bytes: got: %d; want 20", b.result.Bytes)
+			}
+		},
+	}, {
+		desc: "bytes set by some benchmarks",
+		// In this case the bytes result is meaningless, so it must be 0.
+		f: func(b *B) {
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			b.Run("", func(b *B) { work(b) })
+			b.Run("", func(b *B) { b.SetBytes(10); work(b) })
+			if b.result.Bytes != 0 {
+				t.Errorf("bytes: got: %d; want 0", b.result.Bytes)
+			}
+		},
+	}, {
+		desc:   "failure carried over to root",
+		failed: true,
+		output: "--- FAIL: root",
+		f:      func(b *B) { b.Fail() },
+	}, {
+		desc:   "skipping without message, chatty",
+		chatty: true,
+		output: "--- SKIP: root",
+		f:      func(b *B) { b.SkipNow() },
+	}, {
+		desc:   "chatty with recursion",
+		chatty: true,
+		f: func(b *B) {
+			b.Run("", func(b *B) {
+				b.Run("", func(b *B) {})
+			})
+		},
+	}, {
+		desc: "skipping without message, not chatty",
+		f:    func(b *B) { b.SkipNow() },
+	}, {
+		desc:   "skipping after error",
+		failed: true,
+		output: `
+--- FAIL: root
+    sub_test.go:NNN: an error
+    sub_test.go:NNN: skipped`,
+		f: func(b *B) {
+			b.Error("an error")
+			b.Skip("skipped")
+		},
+	}, {
+		desc: "memory allocation",
+		f: func(b *B) {
+			const bufSize = 256
+			alloc := func(b *B) {
+				var buf [bufSize]byte
+				for i := 0; i < b.N; i++ {
+					_ = append([]byte(nil), buf[:]...)
+				}
+			}
+			b.Run("", func(b *B) {
+				alloc(b)
+				b.ReportAllocs()
+			})
+			b.Run("", func(b *B) {
+				alloc(b)
+				b.ReportAllocs()
+			})
+			// runtime.MemStats sometimes reports more allocations than the
+			// benchmark is responsible for. Luckily the point of this test is
+			// to ensure that the results are not underreported, so we can
+			// simply verify the lower bound.
+			if got := b.result.MemAllocs; got < 2 {
+				t.Errorf("MemAllocs was %v; want 2", got)
+			}
+			if got := b.result.MemBytes; got < 2*bufSize {
+				t.Errorf("MemBytes was %v; want %v", got, 2*bufSize)
+			}
+		},
+	}, {
+		desc: "cleanup is called",
+		f: func(b *B) {
+			var calls, cleanups, innerCalls, innerCleanups int
+			b.Run("", func(b *B) {
+				calls++
+				b.Cleanup(func() {
+					cleanups++
+				})
+				b.Run("", func(b *B) {
+					b.Cleanup(func() {
+						innerCleanups++
+					})
+					innerCalls++
+				})
+				work(b)
+			})
+			if calls == 0 || calls != cleanups {
+				t.Errorf("mismatched cleanups; got %d want %d", cleanups, calls)
+			}
+			if innerCalls == 0 || innerCalls != innerCleanups {
+				t.Errorf("mismatched cleanups; got %d want %d", cleanups, calls)
+			}
+		},
+	}, {
+		desc:   "cleanup is called on failure",
+		failed: true,
+		f: func(b *B) {
+			var calls, cleanups int
+			b.Run("", func(b *B) {
+				calls++
+				b.Cleanup(func() {
+					cleanups++
+				})
+				b.Fatalf("failure")
+			})
+			if calls == 0 || calls != cleanups {
+				t.Errorf("mismatched cleanups; got %d want %d", cleanups, calls)
+			}
+		},
+	}}
+	hideStdoutForTesting = true
+	defer func() {
+		hideStdoutForTesting = false
+	}()
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *T) {
+			var ok bool
+			buf := &strings.Builder{}
+			// This is almost like the Benchmark function, except that we override
+			// the benchtime and catch the failure result of the subbenchmark.
+			root := &B{
+				common: common{
+					signal: make(chan bool),
+					name:   "root",
+					w:      buf,
+				},
+				benchFunc: func(b *B) { ok = b.Run("test", tc.f) }, // Use Run to catch failure.
+				benchTime: durationOrCountFlag{d: 1 * time.Microsecond},
+			}
+			if tc.chatty {
+				root.chatty = newChattyPrinter(root.w)
+			}
+			root.runN(1)
+			if ok != !tc.failed {
+				t.Errorf("%s:ok: got %v; want %v", tc.desc, ok, !tc.failed)
+			}
+			if !ok != root.Failed() {
+				t.Errorf("%s:root failed: got %v; want %v", tc.desc, !ok, root.Failed())
+			}
+			// All tests are run as subtests
+			if root.result.N != 1 {
+				t.Errorf("%s: N for parent benchmark was %d; want 1", tc.desc, root.result.N)
+			}
+			got := strings.TrimSpace(buf.String())
+			want := strings.TrimSpace(tc.output)
+			re := makeRegexp(want)
+			if ok, err := regexp.MatchString(re, got); !ok || err != nil {
+				t.Errorf("%s:output:\ngot:\n%s\nwant:\n%s", tc.desc, got, want)
+			}
+		})
+	}
+}
+
+func makeRegexp(s string) string {
+	s = regexp.QuoteMeta(s)
+	s = strings.ReplaceAll(s, "^V", "\x16")
+	s = strings.ReplaceAll(s, ":NNN:", `:\d\d\d\d?:`)
+	s = strings.ReplaceAll(s, "N\\.NNs", `\d*\.\d*s`)
+	return s
+}
+
+func TestBenchmarkOutput(t *T) {
+	// Ensure Benchmark initialized common.w by invoking it with an error and
+	// normal case.
+	Benchmark(func(b *B) { b.Error("do not print this output") })
+	Benchmark(func(b *B) {})
+}
+
+func TestBenchmarkStartsFrom1(t *T) {
+	var first = true
+	Benchmark(func(b *B) {
+		if first && b.N != 1 {
+			panic(fmt.Sprintf("Benchmark() first N=%v; want 1", b.N))
+		}
+		first = false
+	})
+}
+
+func TestBenchmarkReadMemStatsBeforeFirstRun(t *T) {
+	var first = true
+	Benchmark(func(b *B) {
+		if first && (b.startAllocs == 0 || b.startBytes == 0) {
+			panic("ReadMemStats not called before first run")
+		}
+		first = false
+	})
+}
+
+type funcWriter struct {
+	write func([]byte) (int, error)
+}
+
+func (fw *funcWriter) Write(b []byte) (int, error) {
+	return fw.write(b)
+}
+
+func TestRacyOutput(t *T) {
+	var runs int32  // The number of running Writes
+	var races int32 // Incremented for each race detected
+	raceDetector := func(b []byte) (int, error) {
+		// Check if some other goroutine is concurrently calling Write.
+		if atomic.LoadInt32(&runs) > 0 {
+			atomic.AddInt32(&races, 1) // Race detected!
+		}
+		atomic.AddInt32(&runs, 1)
+		defer atomic.AddInt32(&runs, -1)
+		runtime.Gosched() // Increase probability of a race
+		return len(b), nil
+	}
+
+	root := &T{
+		common:  common{w: &funcWriter{raceDetector}},
+		context: newTestContext(1, allMatcher()),
+	}
+	root.chatty = newChattyPrinter(root.w)
+	root.Run("", func(t *T) {
+		var wg sync.WaitGroup
+		for i := 0; i < 100; i++ {
+			wg.Add(1)
+			go func(i int) {
+				defer wg.Done()
+				t.Run(fmt.Sprint(i), func(t *T) {
+					t.Logf("testing run %d", i)
+				})
+			}(i)
+		}
+		wg.Wait()
+	})
+
+	if races > 0 {
+		t.Errorf("detected %d racy Writes", races)
+	}
+}
+
+// The late log message did not include the test name.  Issue 29388.
+func TestLogAfterComplete(t *T) {
+	ctx := newTestContext(1, allMatcher())
+	var buf bytes.Buffer
+	t1 := &T{
+		common: common{
+			// Use a buffered channel so that tRunner can write
+			// to it although nothing is reading from it.
+			signal: make(chan bool, 1),
+			w:      &buf,
+		},
+		context: ctx,
+	}
+
+	c1 := make(chan bool)
+	c2 := make(chan string)
+	tRunner(t1, func(t *T) {
+		t.Run("TestLateLog", func(t *T) {
+			go func() {
+				defer close(c2)
+				defer func() {
+					p := recover()
+					if p == nil {
+						c2 <- "subtest did not panic"
+						return
+					}
+					s, ok := p.(string)
+					if !ok {
+						c2 <- fmt.Sprintf("subtest panic with unexpected value %v", p)
+						return
+					}
+					const want = "Log in goroutine after TestLateLog has completed: log after test"
+					if !strings.Contains(s, want) {
+						c2 <- fmt.Sprintf("subtest panic %q does not contain %q", s, want)
+					}
+				}()
+
+				<-c1
+				t.Log("log after test")
+			}()
+		})
+	})
+	close(c1)
+
+	if s := <-c2; s != "" {
+		t.Error(s)
+	}
+}
+
+func TestBenchmark(t *T) {
+	if Short() {
+		t.Skip("skipping in short mode")
+	}
+	res := Benchmark(func(b *B) {
+		for i := 0; i < 5; i++ {
+			b.Run("", func(b *B) {
+				for i := 0; i < b.N; i++ {
+					time.Sleep(time.Millisecond)
+				}
+			})
+		}
+	})
+	if res.NsPerOp() < 4000000 {
+		t.Errorf("want >5ms; got %v", time.Duration(res.NsPerOp()))
+	}
+}
+
+func TestCleanup(t *T) {
+	var cleanups []int
+	t.Run("test", func(t *T) {
+		t.Cleanup(func() { cleanups = append(cleanups, 1) })
+		t.Cleanup(func() { cleanups = append(cleanups, 2) })
+	})
+	if got, want := cleanups, []int{2, 1}; !reflect.DeepEqual(got, want) {
+		t.Errorf("unexpected cleanup record; got %v want %v", got, want)
+	}
+}
+
+func TestConcurrentCleanup(t *T) {
+	cleanups := 0
+	t.Run("test", func(t *T) {
+		var wg sync.WaitGroup
+		wg.Add(2)
+		for i := 0; i < 2; i++ {
+			i := i
+			go func() {
+				t.Cleanup(func() {
+					// Although the calls to Cleanup are concurrent, the functions passed
+					// to Cleanup should be called sequentially, in some nondeterministic
+					// order based on when the Cleanup calls happened to be scheduled.
+					// So these assignments to the cleanups variable should not race.
+					cleanups |= 1 << i
+				})
+				wg.Done()
+			}()
+		}
+		wg.Wait()
+	})
+	if cleanups != 1|2 {
+		t.Errorf("unexpected cleanup; got %d want 3", cleanups)
+	}
+}
+
+func TestCleanupCalledEvenAfterGoexit(t *T) {
+	cleanups := 0
+	t.Run("test", func(t *T) {
+		t.Cleanup(func() {
+			cleanups++
+		})
+		t.Cleanup(func() {
+			runtime.Goexit()
+		})
+	})
+	if cleanups != 1 {
+		t.Errorf("unexpected cleanup count; got %d want 1", cleanups)
+	}
+}
+
+func TestRunCleanup(t *T) {
+	outerCleanup := 0
+	innerCleanup := 0
+	t.Run("test", func(t *T) {
+		t.Cleanup(func() { outerCleanup++ })
+		t.Run("x", func(t *T) {
+			t.Cleanup(func() { innerCleanup++ })
+		})
+	})
+	if innerCleanup != 1 {
+		t.Errorf("unexpected inner cleanup count; got %d want 1", innerCleanup)
+	}
+	if outerCleanup != 1 {
+		t.Errorf("unexpected outer cleanup count; got %d want 0", outerCleanup)
+	}
+}
+
+func TestCleanupParallelSubtests(t *T) {
+	ranCleanup := 0
+	t.Run("test", func(t *T) {
+		t.Cleanup(func() { ranCleanup++ })
+		t.Run("x", func(t *T) {
+			t.Parallel()
+			if ranCleanup > 0 {
+				t.Error("outer cleanup ran before parallel subtest")
+			}
+		})
+	})
+	if ranCleanup != 1 {
+		t.Errorf("unexpected cleanup count; got %d want 1", ranCleanup)
+	}
+}
+
+func TestNestedCleanup(t *T) {
+	ranCleanup := 0
+	t.Run("test", func(t *T) {
+		t.Cleanup(func() {
+			if ranCleanup != 2 {
+				t.Errorf("unexpected cleanup count in first cleanup: got %d want 2", ranCleanup)
+			}
+			ranCleanup++
+		})
+		t.Cleanup(func() {
+			if ranCleanup != 0 {
+				t.Errorf("unexpected cleanup count in second cleanup: got %d want 0", ranCleanup)
+			}
+			ranCleanup++
+			t.Cleanup(func() {
+				if ranCleanup != 1 {
+					t.Errorf("unexpected cleanup count in nested cleanup: got %d want 1", ranCleanup)
+				}
+				ranCleanup++
+			})
+		})
+	})
+	if ranCleanup != 3 {
+		t.Errorf("unexpected cleanup count: got %d want 3", ranCleanup)
+	}
+}