chore: exit with an error on unknown cli arguments

Author: kmruiz

src/common/config.ts

@@ -306,7 +306,13 @@ function parseCliConfig(args: string[]): CliOptions {
     // so we don't have a logger. For stdio, the warning will be received as a string in
     // the client and IDEs like VSCode do show the message in the log window. For HTTP,
     // it will be in the stdout of the process.
-    warnAboutDeprecatedOrUnknownCliArgs({ ...parsed, _: positionalArguments }, console.warn);
+    warnAboutDeprecatedOrUnknownCliArgs(
+        { ...parsed, _: positionalArguments },
+        {
+            warn: console.warn,
+            exit: process.exit,
+        }
+    );
 
     // if we have a positional argument that matches a connection string
     // store it as the connection specifier and remove it from the argument
@@ -319,7 +325,10 @@ function parseCliConfig(args: string[]): CliOptions {
     return parsed;
 }
 
-export function warnAboutDeprecatedOrUnknownCliArgs(args: Record<string, unknown>, warn: (msg: string) => void): void {
+export function warnAboutDeprecatedOrUnknownCliArgs(
+    args: Record<string, unknown>,
+    { warn, exit }: { warn: (msg: string) => void; exit: (status: number) => void | never }
+): void {
     let usedDeprecatedArgument = false;
     let usedInvalidArgument = false;
 
@@ -353,6 +362,10 @@ export function warnAboutDeprecatedOrUnknownCliArgs(args: Record<string, unknown
     if (usedInvalidArgument || usedDeprecatedArgument) {
         warn("Refer to https://www.mongodb.com/docs/mcp-server/get-started/ for setting up the MCP Server.");
     }
+
+    if (usedInvalidArgument) {
+        exit(1);
+    }
 }
 
 function commaSeparatedToArray<T extends string[]>(str: string | string[] | undefined): T {

tests/unit/common/config.test.ts

@@ -655,12 +655,14 @@ describe("CLI arguments", () => {
         describe(`deprecation behaviour of ${cliArg}`, () => {
             let cliArgs: CliOptions & UserConfig & { _?: string[] };
             let warn: (msg: string) => void;
+            let exit: (status: number) => void | never;
 
             beforeEach(() => {
                 cliArgs = { [cliArg]: "RandomString" } as unknown as CliOptions & UserConfig & { _?: string[] };
                 warn = vi.fn();
+                exit = vi.fn();
 
-                warnAboutDeprecatedOrUnknownCliArgs(cliArgs as unknown as Record<string, unknown>, warn);
+                warnAboutDeprecatedOrUnknownCliArgs(cliArgs as unknown as Record<string, unknown>, { warn, exit });
             });
 
             it(`warns the usage of ${cliArg} as it is deprecated`, () => {
@@ -670,22 +672,28 @@ describe("CLI arguments", () => {
             it(`shows the reference message when ${cliArg} was passed`, () => {
                 expect(warn).toHaveBeenCalledWith(referDocMessage);
             });
+
+            it(`should not exit the process`, () => {
+                expect(exit).not.toHaveBeenCalled();
+            });
         });
     }
 
     describe("invalid arguments", () => {
         let warn: (msg: string) => void;
+        let exit: (status: number) => void | never;
 
         beforeEach(() => {
             warn = vi.fn();
+            exit = vi.fn();
         });
 
         it("should show a warning when an argument is not known", () => {
             warnAboutDeprecatedOrUnknownCliArgs(
                 {
                     wakanda: "",
                 },
-                warn
+                { warn, exit }
             );
 
             expect(warn).toHaveBeenCalledWith("Invalid command line argument 'wakanda'.");
@@ -694,12 +702,23 @@ describe("CLI arguments", () => {
             );
         });
 
+        it("should exit the process on unknown cli args", () => {
+            warnAboutDeprecatedOrUnknownCliArgs(
+                {
+                    wakanda: "",
+                },
+                { warn, exit }
+            );
+
+            expect(exit).toHaveBeenCalledWith(1);
+        });
+
         it("should show a suggestion when is a simple typo", () => {
             warnAboutDeprecatedOrUnknownCliArgs(
                 {
                     readonli: "",
                 },
-                warn
+                { warn, exit }
             );
 
             expect(warn).toHaveBeenCalledWith("Invalid command line argument 'readonli'. Did you mean 'readOnly'?");
@@ -713,7 +732,7 @@ describe("CLI arguments", () => {
                 {
                     readonly: "",
                 },
-                warn
+                { warn, exit }
             );
 
             expect(warn).toHaveBeenCalledWith("Invalid command line argument 'readonly'. Did you mean 'readOnly'?");