TEMP: Add integration test for fallback toolchain

src/test/shell/bazel/cc_integration_test.sh

@@ -1456,4 +1456,26 @@ EOF
   expect_log "fatal error: '\?dep.h'\?"
 }
 
+function test_fallback_to_non_xcode_toolchain() {
+  # This test should trivially pass on platforms other than macOS, so there is no need to exclude
+  # it.
+
+  cat > ok.cc <<EOF
+#include <stdio.h>
+int main() {
+  printf("Hello\n");
+}
+EOF
+
+  cat > BUILD <<EOF
+cc_binary(
+  name = "ok",
+  srcs = ["ok.cc"],
+)
+EOF
+
+  DEVELOPER_DIR=/does_not_exist bazel build '//:ok' || \
+    fail "Should pass with fallback non-Xcode toolchain"
+}
+
 run_suite "cc_integration_test"