cmd/go: convert TestCoverageRuns to the script framework

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: Ie46118eddbd7c3ed0bb9ecee4bdc1cb6fdaf06a0
Reviewed-on: https://go-review.googlesource.com/c/go/+/214291
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/go_test.go

@@ -1709,27 +1709,6 @@ func TestShadowingLogic(t *testing.T) {
 	}
 }
 
-// Check that coverage analysis works at all.
-// Don't worry about the exact numbers but require not 0.0%.
-func checkCoverage(tg *testgoData, data string) {
-	tg.t.Helper()
-	if regexp.MustCompile(`[^0-9]0\.0%`).MatchString(data) {
-		tg.t.Error("some coverage results are 0.0%")
-	}
-}
-
-func TestCoverageRuns(t *testing.T) {
-	skipIfGccgo(t, "gccgo has no cover tool")
-	tooSlow(t)
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.run("test", "-short", "-coverpkg=strings", "strings", "regexp")
-	data := tg.getStdout() + tg.getStderr()
-	tg.run("test", "-short", "-cover", "strings", "math", "regexp")
-	data += tg.getStdout() + tg.getStderr()
-	checkCoverage(tg, data)
-}
-
 func TestBuildDryRunWithCgo(t *testing.T) {
 	if !canCgo {
 		t.Skip("skipping because cgo not enabled")

src/cmd/go/testdata/script/cover_runs.txt

@@ -0,0 +1,13 @@
+[gccgo] skip 'gccgo has no cover tool'
+[short] skip
+
+go test -short -coverpkg=strings strings regexp
+! stdout '[^0-9]0\.0%'
+stdout  'strings.*coverage:.*[1-9][0-9.]+%'
+stdout  'regexp.*coverage:.*[1-9][0-9.]+%'
+
+go test -short -cover strings math regexp
+! stdout '[^0-9]0\.0%'
+stdout  'strings.*coverage:.*[1-9][0-9.]+%'
+stdout  'math.*coverage:.*[1-9][0-9.]+%'
+stdout  'regexp.*coverage:.*[1-9][0-9.]+%'