src/config/index.ts (1)

21-21: Option: include package version in UA for better telemetry.

Consider appending the library version (e.g., "mailtrap-mcp/1.2.3 (...)"). Implement in get-agent.ts to keep config static.

src/lib/get-agent.ts (4)

23-30: Make cwd-based detection case-insensitive.

Paths can differ in case across platforms; normalize before matching.

Apply this diff:

 function isWorkingDirectoryMCP(): boolean {
   try {
     const cwd = process.cwd();
-    return cwd.includes("mailtrap-mcp") && !cwd.includes("node_modules");
+    const lower = cwd.toLowerCase();
+    return lower.includes("mailtrap-mcp") && !lower.includes("node_modules");
   } catch {
     return false;
   }
 }

---

36-44: Broaden self-exclusion and normalize case in stack-based detection.

Also exclude node_modules/mailtrap-nodejs to avoid false positives when this lib is on the stack.

Apply this diff:

 function isCallStackMCP(): boolean {
-  const { stack } = new Error();
-
-  return !!(
-    stack &&
-    stack.includes("mailtrap-mcp") &&
-    !stack.includes("node_modules/mailtrap")
-  );
+  const { stack } = new Error();
+  const lower = stack?.toLowerCase();
+  return !!(
+    lower &&
+    lower.includes("mailtrap-mcp") &&
+    !/node_modules\/mailtrap(-nodejs)?/.test(lower)
+  );
 }

---

59-61: Allow env override and ensure robust fallback.

Let users force UA selection and guard against unexpected undefineds.

Apply this diff:

-function getDynamicUserAgent(): string {
-  return isMailtrapMCPContext() ? MCP_USER_AGENT : USER_AGENT;
-}
+function getDynamicUserAgent(): string {
+  const override = process.env.MAILTRAP_UA?.toLowerCase();
+  if (override === "mcp") return MCP_USER_AGENT;
+  if (override === "default") return USER_AGENT;
+  const ua = isMailtrapMCPContext() ? MCP_USER_AGENT : USER_AGENT;
+  return ua || "mailtrap-nodejs";
+}

---

59-61: Optional: add version to UA string.

If resolveJsonModule is enabled, append package version for traceability (example implementation):

// at top-level (outside selected range):
// import { version } from "../../package.json";

// inside getDynamicUserAgent():
// const base = isMailtrapMCPContext() ? MCP_USER_AGENT : USER_AGENT;
// return `${base}/${version}`;

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src/__tests__/lib/get-agent.test.ts (12)

41-41: Use jest.spyOn instead of reassigning process.cwd

Reassigning globals is brittle and hard to restore. Spy on it instead.

Apply:

-process.cwd = jest.fn().mockReturnValue("/path/to/mailtrap-mcp");
+jest.spyOn(process, "cwd").mockReturnValue("/path/to/mailtrap-mcp");

---

54-56: Use jest.spyOn for process.cwd here as well

Repeat the spy pattern.

Apply:

-process.cwd = jest
-  .fn()
-  .mockReturnValue("/path/to/node_modules/mailtrap-mcp");
+jest.spyOn(process, "cwd").mockReturnValue(
+  "/path/to/node_modules/mailtrap-mcp"
+);

---

68-70: Mock cwd error via spy, not reassignment

This keeps the original method intact.

Apply:

-process.cwd = jest.fn().mockImplementation(() => {
-  throw new Error("Permission denied");
-});
+jest.spyOn(process, "cwd").mockImplementation(() => {
+  throw new Error("Permission denied");
+});

---

91-91: Same here: prefer a spy for process.cwd

Apply:

-process.cwd = jest.fn().mockReturnValue("/path/to/regular-app");
+jest.spyOn(process, "cwd").mockReturnValue("/path/to/regular-app");

---

112-112: Prefer spy over direct assignment

Apply:

-process.cwd = jest.fn().mockReturnValue("/path/to/regular-app");
+jest.spyOn(process, "cwd").mockReturnValue("/path/to/regular-app");

---

133-133: Prefer spy over direct assignment

Apply:

-process.cwd = jest.fn().mockReturnValue("/path/to/regular-app");
+jest.spyOn(process, "cwd").mockReturnValue("/path/to/regular-app");

---

149-149: Prefer spy over direct assignment

Apply:

-process.cwd = jest.fn().mockReturnValue("/path/to/regular-app");
+jest.spyOn(process, "cwd").mockReturnValue("/path/to/regular-app");

---

162-165: Combine both mocks using spies and real Error

Also prefer returning a real Error with overridden stack to preserve instanceof and other semantics.

Apply:

-process.cwd = jest.fn().mockImplementation(() => {
-  throw new Error("Permission denied");
-});
-global.Error = jest.fn().mockImplementation(() => ({
-  stack: undefined,
-})) as any;
+jest.spyOn(process, "cwd").mockImplementation(() => {
+  throw new Error("Permission denied");
+});
+global.Error = jest.fn().mockImplementation(() => {
+  const e = new originalError("Test error");
+  Object.defineProperty(e, "stack", { value: undefined });
+  return e;
+}) as any;

Tip: apply the “real Error with overridden stack” pattern to other stack-based tests, too (Lines 82-89, 102-109, 124-131, 145-147).

---

181-183: Prefer spy over direct assignment

Apply:

-process.cwd = jest
-  .fn()
-  .mockReturnValue("/Users/user/projects/mailtrap-mcp");
+jest.spyOn(process, "cwd").mockReturnValue(
+  "/Users/user/projects/mailtrap-mcp"
+);

---

195-195: Prefer spy over direct assignment

Apply:

-process.cwd = jest.fn().mockReturnValue("/Users/user/projects/my-app");
+jest.spyOn(process, "cwd").mockReturnValue("/Users/user/projects/my-app");

---

82-89: Return a real Error instance with a mocked stack

Returning a plain object breaks Error semantics. Use the original constructor and override stack.

Apply:

-global.Error = jest.fn().mockImplementation(() => ({
-  stack: `
-Error: Test error
-    at Object.<anonymous> (/path/to/mailtrap-mcp/index.js:10:1)
-    at Module._compile (internal/modules/cjs/loader.js:1063:30)
-        `,
-})) as any;
+global.Error = jest.fn().mockImplementation(() => {
+  const e = new originalError("Test error");
+  Object.defineProperty(e, "stack", {
+    value: `
+Error: Test error
+    at Object.<anonymous> (/path/to/mailtrap-mcp/index.js:10:1)
+    at Module._compile (internal/modules/cjs/loader.js:1063:30)
+        `,
+  });
+  return e;
+}) as any;

---

206-256: Strengthen the integration test: assert getDynamicUserAgent is used

Right now it only checks client is created. Mock get-agent and assert it’s called during client construction. Also align the config mock to default-export shape.

Apply:

-      jest.doMock("../../config", () => ({
-        CLIENT_SETTINGS: {
+      jest.doMock("../../config", () => ({
+        __esModule: true,
+        default: {
+          CLIENT_SETTINGS: {
             SENDING_ENDPOINT: "https://send.api.mailtrap.io",
             BULK_ENDPOINT: "https://bulk.api.mailtrap.io",
             TESTING_ENDPOINT: "https://sandbox.api.mailtrap.io",
             GENERAL_ENDPOINT: "https://mailtrap.io",
             USER_AGENT:
               "mailtrap-nodejs (https://github.com/railsware/mailtrap-nodejs)",
             MCP_USER_AGENT:
               "mailtrap-mcp (https://github.com/railsware/mailtrap-mcp)",
             MAX_REDIRECTS: 0,
             TIMEOUT: 10000,
-        },
-        ERRORS: {
+          },
+          ERRORS: {
             FILENAME_REQUIRED: "Filename is required.",
             CONTENT_REQUIRED: "Content is required.",
             SUBJECT_REQUIRED: "Subject is required.",
             FROM_REQUIRED: "From is required.",
             SENDING_FAILED: "Sending failed.",
             NO_DATA_ERROR: "No Data.",
             TEST_INBOX_ID_MISSING:
               "testInboxId is missing, testing API will not work.",
             ACCOUNT_ID_MISSING:
               "accountId is missing, some features of testing API may not work properly.",
             BULK_SANDBOX_INCOMPATIBLE:
               "Bulk mode is not applicable for sandbox API.",
-        },
-        TRANSPORT_SETTINGS: {
-          NAME: "MailtrapTransport",
-        },
+          },
+          TRANSPORT_SETTINGS: {
+            NAME: "MailtrapTransport",
+          },
+        },
       }));
 
+      const getAgentMock = jest.fn(() => "ua-from-test");
+      jest.doMock("../../lib/get-agent", () => ({
+        __esModule: true,
+        default: getAgentMock,
+      }));
+
       // Clear module cache and re-import
       jest.resetModules();
       const { default: MailtrapClient } = jest.requireActual(
         "../../lib/MailtrapClient"
       );
@@
-      // The User-Agent should be set in the axios instance
-      // We can't easily test the internal axios instance, but we can verify
-      // that the function is called during client creation
-      expect(client).toBeDefined();
+      // Ensure dynamic UA is consulted during client creation
+      expect(client).toBeDefined();
+      expect(getAgentMock).toHaveBeenCalledTimes(1);

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro