cmd/fix: move cgo and 'go build' support checks into TestRewrite

This avoids unnecessary work to determine 'go build' and cgo support
if we're not actually running the test (as in 'go test -list').

Change-Id: Id175a759605b2130d4de8bff8eba4c23fe65ccba
Reviewed-on: https://go-review.googlesource.com/c/go/+/491657
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Austin Clements <austin@google.com>

diff --git a/src/cmd/fix/main_test.go b/src/cmd/fix/main_test.go
index 2b293077d13f6df09d8b5373cd57bc7ae1c0f408..cafd116cfd6b357f5737d2a77db7bb4bd6a0cb93 100644 (file)
--- a/src/cmd/fix/main_test.go
+++ b/src/cmd/fix/main_test.go
@@ -14,20 +14,6 @@ import (
        "testing"
 )
 
-func init() {
-       // If cgo is enabled, enforce that cgo commands invoked by cmd/fix
-       // do not fail during testing.
-       if testenv.HasCGO() && testenv.HasGoBuild() {
-               // The reportCgoError hook is global, so we can't set it per-test
-               // if we want to be able to run those tests in parallel.
-               // Instead, simply set it to panic on error: the goroutine dump
-               // from the panic should help us determine which test failed.
-               reportCgoError = func(err error) {
-                       panic(fmt.Sprintf("unexpected cgo error: %v", err))
-               }
-       }
-}
-
 type testCase struct {
        Name    string
        Fn      func(*ast.File) bool
@@ -91,6 +77,22 @@ func parseFixPrint(t *testing.T, fn func(*ast.File) bool, desc, in string, mustB
 }
 
 func TestRewrite(t *testing.T) {
+       // If cgo is enabled, enforce that cgo commands invoked by cmd/fix
+       // do not fail during testing.
+       if testenv.HasCGO() {
+               testenv.MustHaveGoBuild(t) // Really just 'go tool cgo', but close enough.
+
+               // The reportCgoError hook is global, so we can't set it per-test
+               // if we want to be able to run those tests in parallel.
+               // Instead, simply set it to panic on error: the goroutine dump
+               // from the panic should help us determine which test failed.
+               prevReportCgoError := reportCgoError
+               reportCgoError = func(err error) {
+                       panic(fmt.Sprintf("unexpected cgo error: %v", err))
+               }
+               t.Cleanup(func() { reportCgoError = prevReportCgoError })
+       }
+
        for _, tt := range testCases {
                tt := tt
                t.Run(tt.Name, func(t *testing.T) {