testing: allow go test -run=^$ testing

This should fix the ssacheck builder.

Change-Id: I4b6172df33d6447f7ec8fd8e301c6380efb92588
Reviewed-on: https://go-review.googlesource.com/c/go/+/431336
Auto-Submit: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/testing/testing.go b/src/testing/testing.go
index e3460e049da28193e81df3410eb1ca7525be0b85..81268ec61f66683eb1cd808b09f3c9e08fe7176e 100644 (file)
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -1766,12 +1766,13 @@ func (m *M) Run() (code int) {
                m.stopAlarm()
                if !testRan && !exampleRan && !fuzzTargetsRan && *matchBenchmarks == "" && *matchFuzz == "" {
                        fmt.Fprintln(os.Stderr, "testing: warning: no tests to run")
-                       if testingTesting {
+                       if testingTesting && *match != "^$" {
                                // If this happens during testing of package testing it could be that
                                // package testing's own logic for when to run a test is broken,
                                // in which case every test will run nothing and succeed,
                                // with no obvious way to detect this problem (since no tests are running).
                                // So make 'no tests to run' a hard failure when testing package testing itself.
+                               // The compile-only builders use -run=^$ to run no tests, so allow that.
                                fmt.Println("FAIL: package testing must run tests")
                                testOk = false
                        }