cmd/dist: refactor adding to the test list into a method

Currently, there are four places that add distTests to the
tester.tests list. That means we're already missing a few name
uniqueness checks, and we're about to start enforcing some more
requirements on tests that would be nice to have in one place. Hence,
to prepare for this, this CL refactors the process of adding to the
tester.tests list into a method. That also means we can trivially use
a map to check name uniqueness rather than an n^2 slice search.

For #37486.

Change-Id: Ib7b64c7bbf65e5e870c4f4bfaca8c7f70983605c
Reviewed-on: https://go-review.googlesource.com/c/go/+/495015
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/dist/test.go

@@ -70,7 +70,8 @@ type tester struct {
 	cgoEnabled bool
 	partial    bool
 
-	tests        []distTest
+	tests        []distTest // use addTest to extend
+	testNames    map[string]bool
 	timeoutScale int
 
 	worklist []*work
@@ -193,7 +194,7 @@ func (t *tester) run() {
 	}
 
 	for _, name := range t.runNames {
-		if !t.isRegisteredTestName(name) {
+		if !t.testNames[name] {
 			fatalf("unknown test %q", name)
 		}
 	}
@@ -471,31 +472,27 @@ func (t *tester) registerStdTest(pkg string) {
 		stdMatches = append(stdMatches, pkg)
 	}
 
-	t.tests = append(t.tests, distTest{
-		name:    testName,
-		heading: heading,
-		fn: func(dt *distTest) error {
-			if ranGoTest {
-				return nil
-			}
-			t.runPending(dt)
-			timelog("start", dt.name)
-			defer timelog("end", dt.name)
-			ranGoTest = true
+	t.addTest(testName, heading, func(dt *distTest) error {
+		if ranGoTest {
+			return nil
+		}
+		t.runPending(dt)
+		timelog("start", dt.name)
+		defer timelog("end", dt.name)
+		ranGoTest = true
 
-			timeoutSec := 180 * time.Second
-			for _, pkg := range stdMatches {
-				if pkg == "cmd/go" {
-					timeoutSec *= 3
-					break
-				}
+		timeoutSec := 180 * time.Second
+		for _, pkg := range stdMatches {
+			if pkg == "cmd/go" {
+				timeoutSec *= 3
+				break
 			}
-			return (&goTest{
-				timeout: timeoutSec,
-				gcflags: gcflags,
-				pkgs:    stdMatches,
-			}).run(t)
-		},
+		}
+		return (&goTest{
+			timeout: timeoutSec,
+			gcflags: gcflags,
+			pkgs:    stdMatches,
+		}).run(t)
 	})
 }
 
@@ -504,25 +501,21 @@ func (t *tester) registerRaceBenchTest(pkg string) {
 	if t.runRx == nil || t.runRx.MatchString(testName) == t.runRxWant {
 		benchMatches = append(benchMatches, pkg)
 	}
-	t.tests = append(t.tests, distTest{
-		name:    testName,
-		heading: "Running benchmarks briefly.",
-		fn: func(dt *distTest) error {
-			if ranGoBench {
-				return nil
-			}
-			t.runPending(dt)
-			timelog("start", dt.name)
-			defer timelog("end", dt.name)
-			ranGoBench = true
-			return (&goTest{
-				timeout: 1200 * time.Second, // longer timeout for race with benchmarks
-				race:    true,
-				bench:   true,
-				cpu:     "4",
-				pkgs:    benchMatches,
-			}).run(t)
-		},
+	t.addTest(testName, "Running benchmarks briefly.", func(dt *distTest) error {
+		if ranGoBench {
+			return nil
+		}
+		t.runPending(dt)
+		timelog("start", dt.name)
+		defer timelog("end", dt.name)
+		ranGoBench = true
+		return (&goTest{
+			timeout: 1200 * time.Second, // longer timeout for race with benchmarks
+			race:    true,
+			bench:   true,
+			cpu:     "4",
+			pkgs:    benchMatches,
+		}).run(t)
 	})
 }
 
@@ -688,43 +681,39 @@ func (t *tester) registerTests() {
 	// Fails on Android, js/wasm and wasip1/wasm with an exec format error.
 	// Fails on plan9 with "cannot find GOROOT" (issue #21016).
 	if os.Getenv("GO_BUILDER_NAME") != "" && goos != "android" && !t.iOS() && goos != "plan9" && goos != "js" && goos != "wasip1" {
-		t.tests = append(t.tests, distTest{
-			name:    "moved_goroot",
-			heading: "moved GOROOT",
-			fn: func(dt *distTest) error {
-				t.runPending(dt)
-				timelog("start", dt.name)
-				defer timelog("end", dt.name)
-				moved := goroot + "-moved"
-				if err := os.Rename(goroot, moved); err != nil {
-					if goos == "windows" {
-						// Fails on Windows (with "Access is denied") if a process
-						// or binary is in this directory. For instance, using all.bat
-						// when run from c:\workdir\go\src fails here
-						// if GO_BUILDER_NAME is set. Our builders invoke tests
-						// a different way which happens to work when sharding
-						// tests, but we should be tolerant of the non-sharded
-						// all.bat case.
-						log.Printf("skipping test on Windows")
-						return nil
-					}
-					return err
-				}
-
-				// Run `go test fmt` in the moved GOROOT, without explicitly setting
-				// GOROOT in the environment. The 'go' command should find itself.
-				cmd := (&goTest{
-					goroot: moved,
-					pkg:    "fmt",
-				}).command(t)
-				unsetEnv(cmd, "GOROOT")
-				err := cmd.Run()
-
-				if rerr := os.Rename(moved, goroot); rerr != nil {
-					fatalf("failed to restore GOROOT: %v", rerr)
+		t.addTest("moved_goroot", "moved GOROOT", func(dt *distTest) error {
+			t.runPending(dt)
+			timelog("start", dt.name)
+			defer timelog("end", dt.name)
+			moved := goroot + "-moved"
+			if err := os.Rename(goroot, moved); err != nil {
+				if goos == "windows" {
+					// Fails on Windows (with "Access is denied") if a process
+					// or binary is in this directory. For instance, using all.bat
+					// when run from c:\workdir\go\src fails here
+					// if GO_BUILDER_NAME is set. Our builders invoke tests
+					// a different way which happens to work when sharding
+					// tests, but we should be tolerant of the non-sharded
+					// all.bat case.
+					log.Printf("skipping test on Windows")
+					return nil
 				}
 				return err
-			},
+			}
+
+			// Run `go test fmt` in the moved GOROOT, without explicitly setting
+			// GOROOT in the environment. The 'go' command should find itself.
+			cmd := (&goTest{
+				goroot: moved,
+				pkg:    "fmt",
+			}).command(t)
+			unsetEnv(cmd, "GOROOT")
+			err := cmd.Run()
+
+			if rerr := os.Rename(moved, goroot); rerr != nil {
+				fatalf("failed to restore GOROOT: %v", rerr)
+			}
+			return err
 		})
 	}
 
@@ -868,15 +857,22 @@ func (t *tester) registerTests() {
 	}
 }
 
-// isRegisteredTestName reports whether a test named testName has already
-// been registered.
-func (t *tester) isRegisteredTestName(testName string) bool {
-	for _, tt := range t.tests {
-		if tt.name == testName {
-			return true
-		}
+// addTest adds an arbitrary test callback to the test list.
+//
+// name must uniquely identify the test.
+func (t *tester) addTest(name, heading string, fn func(*distTest) error) {
+	if t.testNames[name] {
+		panic("duplicate registered test name " + name)
 	}
-	return false
+	if t.testNames == nil {
+		t.testNames = make(map[string]bool)
+	}
+	t.testNames[name] = true
+	t.tests = append(t.tests, distTest{
+		name:    name,
+		heading: heading,
+		fn:      fn,
+	})
 }
 
 type registerTestOpt interface {
@@ -902,29 +898,22 @@ func (t *tester) registerTest(name, heading string, test *goTest, opts ...regist
 			preFunc = opt.pre
 		}
 	}
-	if t.isRegisteredTestName(name) {
-		panic("duplicate registered test name " + name)
-	}
 	if heading == "" {
 		if test.pkg == "" {
 			panic("either heading or test.pkg must be set")
 		}
 		heading = test.pkg
 	}
-	t.tests = append(t.tests, distTest{
-		name:    name,
-		heading: heading,
-		fn: func(dt *distTest) error {
-			if preFunc != nil && !preFunc(dt) {
-				return nil
-			}
-			w := &work{
-				dt:  dt,
-				cmd: test.bgCommand(t),
-			}
-			t.worklist = append(t.worklist, w)
+	t.addTest(name, heading, func(dt *distTest) error {
+		if preFunc != nil && !preFunc(dt) {
 			return nil
-		},
+		}
+		w := &work{
+			dt:  dt,
+			cmd: test.bgCommand(t),
+		}
+		t.worklist = append(t.worklist, w)
+		return nil
 	})
 }