call setupActionsVars in the tests too

src/util.ts

@@ -390,3 +390,19 @@ export async function getGitHubAuth(
     "No GitHub authentication token was specified. Please provide a token via the GITHUB_TOKEN environment variable, or by adding the `--github-auth-stdin` flag and passing the token via standard input."
   );
 }
+
+// Sets environment variables that make using some libraries designed for
+// use only on actions safe to use outside of actions.
+//
+// Obviously this is not a tremendously great thing we're doing and it
+// would be better to write our own implementation of libraries to use
+// outside of actions. For now this works well enough.
+//
+// Currently this list of libraries that is deemed to now be safe includes:
+// - @actions/tool-cache
+//
+// Also see "queries/unguarded-action-lib.ql".
+export function setupActionsVars(tempDir: string, toolsDir: string) {
+  process.env["RUNNER_TEMP"] = tempDir;
+  process.env["RUNNER_TOOL_CACHE"] = toolsDir;
+}