test(oauth): cover exchange-throw logging and guard against raw token leaks

packages/better-auth/src/api/routes/callback.test.ts

@@ -17,7 +17,11 @@ describe("callback", () => {
 			validateAuthorizationCode: async () =>
 				// Mirrors a provider (e.g. Slack) that answers with HTTP 200 but an
 				// error in the response body instead of failing the HTTP request.
-				getOAuth2Tokens({ ok: false, error: "invalid_code" }),
+				getOAuth2Tokens({
+					ok: false,
+					error: "invalid_code",
+					refresh_token: "sensitive-refresh-token",
+				}),
 			getUserInfo: async () => null,
 		} satisfies OAuthProvider<Record<string, never>>;
 
@@ -70,6 +74,66 @@ describe("callback", () => {
 		});
 		// The raw token response must never be logged as-is.
 		expect(JSON.stringify(noTokenCalls[0])).not.toContain('"raw"');
+		expect(JSON.stringify(noTokenCalls[0])).not.toContain(
+			"sensitive-refresh-token",
+		);
+
+		errorSpy.mockRestore();
+	});
+
+	it("logs the provider id when the authorization code exchange throws", async () => {
+		const exchangeError = new Error("token endpoint unreachable");
+		const provider = {
+			id: "throwing-provider",
+			name: "Throwing Provider",
+			accountSubject: () => "subject",
+			createAuthorizationURL: ({ state }) =>
+				new URL(`https://idp.example.com/authorize?state=${state}`),
+			validateAuthorizationCode: async () => {
+				throw exchangeError;
+			},
+			getUserInfo: async () => null,
+		} satisfies OAuthProvider<Record<string, never>>;
+
+		const { client, auth, cookieSetter } = await getTestInstance({
+			plugins: [
+				{
+					id: "throwing-provider-plugin",
+					init: (ctx) => ({
+						context: {
+							socialProviders: [provider, ...ctx.socialProviders],
+						},
+					}),
+				},
+			],
+		});
+
+		const ctx = await auth.$context;
+		const errorSpy = vi.spyOn(ctx.logger, "error").mockImplementation(() => {});
+
+		const oAuthHeaders = new Headers();
+		const signIn = await client.signIn.social(
+			{
+				provider: provider.id,
+				callbackURL: "/dashboard",
+			},
+			{
+				throw: true,
+				onSuccess: cookieSetter(oAuthHeaders),
+			},
+		);
+		const state = new URL(signIn.url!).searchParams.get("state");
+
+		await client.$fetch(`/callback/${provider.id}?code=test&state=${state}`, {
+			method: "GET",
+			headers: oAuthHeaders,
+			onError() {},
+		});
+
+		expect(errorSpy).toHaveBeenCalledWith(
+			"Failed to exchange OAuth authorization code",
+			{ providerId: provider.id, error: exchangeError },
+		);
 
 		errorSpy.mockRestore();
 	});