cmd/go/internal/test: pass default timeout to test programs even if i…

…t is not given from command line

Make 'go test' command to pass the default timeout (10m) to test programs even if the value is not given from command line.

Fixes golang#28147

src/cmd/go/internal/test/test.go

@@ -559,6 +559,9 @@ func runTest(cmd *base.Command, args []string) {
 		testKillTimeout = 100 * 365 * 24 * time.Hour
 	}
 
+	// Pass timeout flag to tests.
+	testArgs = append(testArgs, "-test.timeout="+testKillTimeout.String())
+
 	// show passing test output (after buffering) with -v flag.
 	// must buffer because tests are running in parallel, and
 	// otherwise the output will get mixed.

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

@@ -0,0 +1,21 @@
+env GO111MODULE=off
+cd a
+
+# No timeout is passed via 'go test' command.
+go test -v
+stdout '10m0s'
+
+# Timeout is passed via 'go test' command.
+go test -v -timeout 30m
+stdout '31m0s'
+
+-- a/timeout_test.go --
+package t
+import (
+	"flag"
+	"fmt"
+	"testing"
+)
+func TestTimeout(t *testing.T) {
+	fmt.Println(flag.Lookup("test.timeout").Value.String())
+}