feat: create unit test for UserService

Author: isharghura

test/items/services/UserService.test.ts

@@ -0,0 +1,44 @@
+import { UserService } from "@src/items/services/UserService";
+
+jest.mock("../../../data/githubDiscordMap.json", () => ({
+  alice: {
+    githubUsername: "alice",
+    githubId: "ghid-alice",
+    discordId: "discord-alice",
+  },
+  bob: {
+    githubUsername: "bob",
+    githubId: "ghid-bob",
+    discordId: "discord-bob",
+  },
+}));
+
+describe("UserService", () => {
+  it("finds user by Discord ID", async () => {
+    const result = await UserService.findUserByDiscordID("discord-bob");
+    expect(result.ok).toBe(true);
+
+    if (result.ok) {
+      expect(result.val.githubUsername).toBe("bob");
+    }
+  });
+
+  it("will return error for unknown Discord ID", async () => {
+    const result = await UserService.findUserByDiscordID("unknown");
+    expect(result.err).toBe(true);
+  });
+
+  it("finds user by GitHub username", async () => {
+    const result = await UserService.findUserByGithubUsername("alice");
+    expect(result.ok).toBe(true);
+
+    if (result.ok) {
+      expect(result.val.discordId).toBe("discord-alice");
+    }
+  });
+
+  it("will return error for unknown GitHub username", async () => {
+    const result = await UserService.findUserByGithubUsername("charlie");
+    expect(result.err).toBe(true);
+  });
+});