add test cases for system property of query object

test/resolvers/QueryResolverTests.test.ts

@@ -52,5 +52,19 @@ describe("QueryResolvers", () => {
       expect(response.body.singleResult.errors).toBeUndefined();
       expect(response.body.singleResult.data?.systems).toHaveLength(systems.length);
     });
-  })
+  });
+
+  describe("system", () => {
+    it("returns a system for an ID from the repository", async () => {
+
+    });
+
+    it("returns null if no id provided", async () => {
+
+    });
+
+    it("returns null if there is no system", async () => {
+
+    });
+  });
 });