Add tests for isGhes

__tests__/actionUtils.test.ts

@@ -17,6 +17,24 @@ afterEach(() => {
     delete process.env[RefKey];
 });
 
+test("isGhes returns true if server url is not github.com", () => {
+    try {
+        process.env["GITHUB_SERVER_URL"] = "http://example.com";
+        expect(actionUtils.isGhes()).toBe(true);
+    } finally {
+        process.env["GITHUB_SERVER_URL"] = undefined;
+    }
+});
+
+test("isGhes returns true when server url is github.com", () => {
+    try {
+        process.env["GITHUB_SERVER_URL"] = "http://github.com";
+        expect(actionUtils.isGhes()).toBe(false);
+    } finally {
+        process.env["GITHUB_SERVER_URL"] = undefined;
+    }
+});
+
 test("isExactKeyMatch with undefined cache key returns false", () => {
     const key = "linux-rust";
     const cacheKey = undefined;