runtime/coverage: improve unit tests

Add a testpoint to cover support routines used to help
implement "go test -cover".

Change-Id: Ic28bf884a4e0d2c0a6d8fd04fc29c0c949227f21
Reviewed-on: https://go-review.googlesource.com/c/go/+/432315
Reviewed-by: Bryan Mills <bcmills@google.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/testing/newcover.go b/src/testing/newcover.go
index e90b9c9805..1805f791e6 100644
--- a/src/testing/newcover.go
+++ b/src/testing/newcover.go
@@ -39,3 +39,10 @@ func coverReport2() {
 		os.Exit(2)
 	}
 }
+
+// testGoCoverDir returns the value passed to the -test.gocoverdir
+// flag by the Go command, if goexperiment.CoverageRedesign is
+// in effect.
+func testGoCoverDir() string {
+	return *gocoverdir
+}