[dev.fuzz] testing, internal/fuzz: multiple small fixes

* Run gofmt with go1.17 build constraint changes.
* Tighten regular expressions used in tests. "ok" got some false
  positives with verbose output, so make sure it appears at the start
  of a line.
* Return err in deps.RunFuzzWorker instead of nil.
* Call common.Helper from F methods. This prevents F methods from
  appearing in stack traces.

Change-Id: I839c70ec8a9f313c1a4ea68e6bb34a4d801dd36f
Reviewed-on: https://go-review.googlesource.com/c/go/+/297032
Trust: Jay Conrod <jayconrod@google.com>
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>

2 files changed, 31 insertions, 2 deletions

diff --git a/src/testing/fuzz.go b/src/testing/fuzz.go
index f670ef4546..1a634dbe8b 100644
--- a/src/testing/fuzz.go
+++ b/src/testing/fuzz.go
@@ -70,6 +70,7 @@ func (f *F) Cleanup(fn func()) {
 	if f.inFuzzFn {
 		panic("testing: f.Cleanup was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Cleanup(fn)
 }
 
@@ -78,6 +79,7 @@ func (f *F) Error(args ...interface{}) {
 	if f.inFuzzFn {
 		panic("testing: f.Error was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Error(args...)
 }
 
@@ -86,6 +88,7 @@ func (f *F) Errorf(format string, args ...interface{}) {
 	if f.inFuzzFn {
 		panic("testing: f.Errorf was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Errorf(format, args...)
 }
 
@@ -94,6 +97,7 @@ func (f *F) Fail() {
 	if f.inFuzzFn {
 		panic("testing: f.Fail was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Fail()
 }
 
@@ -109,6 +113,7 @@ func (f *F) FailNow() {
 	if f.inFuzzFn {
 		panic("testing: f.FailNow was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.FailNow()
 }
 
@@ -117,6 +122,7 @@ func (f *F) Fatal(args ...interface{}) {
 	if f.inFuzzFn {
 		panic("testing: f.Fatal was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Fatal(args...)
 }
 
@@ -125,6 +131,7 @@ func (f *F) Fatalf(format string, args ...interface{}) {
 	if f.inFuzzFn {
 		panic("testing: f.Fatalf was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Fatalf(format, args...)
 }
 
@@ -135,7 +142,25 @@ func (f *F) Helper() {
 	if f.inFuzzFn {
 		panic("testing: f.Helper was called inside the f.Fuzz function")
 	}
-	f.common.Helper()
+
+	// common.Helper is inlined here.
+	// If we called it, it would mark F.Helper as the helper
+	// instead of the caller.
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	if f.helperPCs == nil {
+		f.helperPCs = make(map[uintptr]struct{})
+	}
+	// repeating code from callerName here to save walking a stack frame
+	var pc [1]uintptr
+	n := runtime.Callers(2, pc[:]) // skip runtime.Callers + Helper
+	if n == 0 {
+		panic("testing: zero callers found")
+	}
+	if _, found := f.helperPCs[pc[0]]; !found {
+		f.helperPCs[pc[0]] = struct{}{}
+		f.helperNames = nil // map will be recreated next time it is needed
+	}
 }
 
 // Skip is equivalent to Log followed by SkipNow.
@@ -143,6 +168,7 @@ func (f *F) Skip(args ...interface{}) {
 	if f.inFuzzFn {
 		panic("testing: f.Skip was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Skip(args...)
 }
 
@@ -158,6 +184,7 @@ func (f *F) SkipNow() {
 	if f.inFuzzFn {
 		panic("testing: f.SkipNow was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.SkipNow()
 }
 
@@ -166,6 +193,7 @@ func (f *F) Skipf(format string, args ...interface{}) {
 	if f.inFuzzFn {
 		panic("testing: f.Skipf was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	f.common.Skipf(format, args...)
 }
 
@@ -178,6 +206,7 @@ func (f *F) TempDir() string {
 	if f.inFuzzFn {
 		panic("testing: f.TempDir was called inside the f.Fuzz function")
 	}
+	f.common.Helper()
 	return f.common.TempDir()
 }
 
diff --git a/src/testing/internal/testdeps/deps.go b/src/testing/internal/testdeps/deps.go
index d5481d6608..8f587b2e1d 100644
--- a/src/testing/internal/testdeps/deps.go
+++ b/src/testing/internal/testdeps/deps.go
@@ -166,7 +166,7 @@ func (TestDeps) RunFuzzWorker(fn func(fuzz.CorpusEntry) error) error {
 	if err == ctx.Err() {
 		return nil
 	}
-	return nil
+	return err
 }
 
 func (TestDeps) ReadCorpus(dir string, types []reflect.Type) ([]fuzz.CorpusEntry, error) {