test(pav-6): improve branch coverage to meet 80% threshold

- Add unit test for email validation in handleCallback (oauth_email_required)
- Add LinkedIn provider to auth.service mock registry
- Add logInfo test without ctx to cover nullish coalescing branch

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

backend/tests/unit/modules/auth/auth.service.test.ts

@@ -16,6 +16,10 @@ vi.mock("../../../../src/modules/auth/providers/auth.provider", () => ({
       getAuthUrl: mocks.getAuthUrl,
       exchangeCode: mocks.exchangeCode,
     },
+    linkedin: {
+      getAuthUrl: mocks.getAuthUrl,
+      exchangeCode: mocks.exchangeCode,
+    },
   },
 }));
 
@@ -132,6 +136,19 @@ describe("AuthService", () => {
       );
     });
 
+    it("throws when profile has no email", async () => {
+      mocks.exchangeCode.mockResolvedValueOnce({
+        ...mockProfile,
+        email: undefined,
+      });
+
+      await expect(service.handleCallback(validCallbackParams)).rejects.toThrow(
+        "oauth_email_required",
+      );
+
+      expect(mocks.findOrCreateUser).not.toHaveBeenCalled();
+    });
+
     it("calls findOrCreateUser with provider and profile", async () => {
       mocks.exchangeCode.mockResolvedValueOnce(mockProfile);
       mocks.findOrCreateUser.mockResolvedValueOnce(mockUser);

backend/tests/unit/utils/logger.test.ts

@@ -65,6 +65,22 @@ describe("logger", () => {
     vi.resetModules();
   });
 
+  it("logInfo works without ctx", async () => {
+    const spy = vi
+      .spyOn(process.stdout, "write")
+      .mockImplementation(() => true);
+
+    const { logInfo } = await import("../../../src/logger.ts");
+    logInfo("no context");
+
+    const output = spy.mock.calls.map((c) => String(c[0])).join("");
+    const parsed = JSON.parse(output);
+
+    expect(parsed.msg).toBe("no context");
+
+    spy.mockRestore();
+  });
+
   it("defaults to info level", async () => {
     delete process.env.LOG_LEVEL;
     vi.resetModules();