Copy TEST_TMPDIR env variable to TMPDIR before running tests

Author: rickystewart

go/tools/builders/generate_test_main.go

@@ -178,6 +178,13 @@ func main() {
 	// out of the Chdir behavior.
 	_ = os.Unsetenv("GO_TEST_RUN_FROM_BAZEL")
 
+	// NOTE(ricky): Bazel sets the TEST_TMPDIR env variable, but Cockroach
+	// tests generally consult TMPDIR.
+	err := os.Setenv("TMPDIR", os.Getenv("TEST_TMPDIR"))
+	if err != nil {
+		panic(err)
+	}
+
 	if bzltestutil.ShouldWrap() {
 		err := bzltestutil.Wrap("{{.Pkgname}}")
 		exitCode := 0