feat: introduces dry mode for CLI MCP-297 (#747)

himanshusinghs · web-flow · commit 17cdcd1c5eca · 2025-11-26T12:07:20.000+01:00
diff --git a/package.json b/package.json
@@ -66,8 +66,8 @@
     "generate": "pnpm run generate:api && pnpm run generate:arguments",
     "generate:api": "./scripts/generate.sh",
     "generate:arguments": "tsx scripts/generateArguments.ts",
+    "pretest": "pnpm run build",
     "test": "vitest --project eslint-rules --project unit-and-integration --coverage",
-    "pretest:accuracy": "pnpm run build",
     "test:accuracy": "sh ./scripts/accuracy/runAccuracyTests.sh",
     "test:long-running-tests": "vitest --project long-running-tests --coverage",
     "atlas:cleanup": "vitest --project atlas-cleanup"
diff --git a/src/common/config/argsParserOptions.ts b/src/common/config/argsParserOptions.ts
@@ -59,6 +59,7 @@ export const OPTIONS = {
     boolean: [
         "apiDeprecationErrors",
         "apiStrict",
+        "dryRun",
         "embeddingsValidation",
         "help",
         "indexCheck",
diff --git a/src/common/config/userConfig.ts b/src/common/config/userConfig.ts
@@ -173,4 +173,10 @@ export const UserConfigSchema = z4.object({
         )
         .default([])
         .describe("An array of preview features that are enabled."),
+    dryRun: z4
+        .boolean()
+        .default(false)
+        .describe(
+            "When true, runs the server in dry mode: dumps configuration and enabled tools, then exits without starting the server."
+        ),
 });
diff --git a/src/index.ts b/src/index.ts
@@ -44,13 +44,23 @@ import { StdioRunner } from "./transports/stdio.js";
 import { StreamableHttpRunner } from "./transports/streamableHttp.js";
 import { systemCA } from "@mongodb-js/devtools-proxy-support";
 import { Keychain } from "./common/keychain.js";
+import { DryRunModeRunner } from "./transports/dryModeRunner.js";
 
 async function main(): Promise<void> {
     systemCA().catch(() => undefined); // load system CA asynchronously as in mongosh
 
     const config = createUserConfig();
-    assertHelpMode(config);
-    assertVersionMode(config);
+    if (config.help) {
+        handleHelpRequest();
+    }
+
+    if (config.version) {
+        handleVersionRequest();
+    }
+
+    if (config.dryRun) {
+        await handleDryRunRequest(config);
+    }
 
     const transportRunner =
         config.transport === "stdio"
@@ -133,17 +143,35 @@ main().catch((error: unknown) => {
     process.exit(1);
 });
 
-function assertHelpMode(config: UserConfig): void | never {
-    if (config.help) {
-        console.log("For usage information refer to the README.md:");
-        console.log("https://github.com/mongodb-js/mongodb-mcp-server?tab=readme-ov-file#quick-start");
-        process.exit(0);
-    }
+function handleHelpRequest(): never {
+    console.log("For usage information refer to the README.md:");
+    console.log("https://github.com/mongodb-js/mongodb-mcp-server?tab=readme-ov-file#quick-start");
+    process.exit(0);
 }
 
-function assertVersionMode(config: UserConfig): void | never {
-    if (config.version) {
-        console.log(packageInfo.version);
+function handleVersionRequest(): never {
+    console.log(packageInfo.version);
+    process.exit(0);
+}
+
+export async function handleDryRunRequest(config: UserConfig): Promise<never> {
+    try {
+        const runner = new DryRunModeRunner({
+            userConfig: config,
+            logger: {
+                log(message): void {
+                    console.log(message);
+                },
+                error(message): void {
+                    console.error(message);
+                },
+            },
+        });
+        await runner.start();
+        await runner.close();
         process.exit(0);
+    } catch (error) {
+        console.error(`Fatal error running server in dry run mode: ${error as string}`);
+        process.exit(1);
     }
 }
diff --git a/src/transports/dryModeRunner.ts b/src/transports/dryModeRunner.ts
@@ -0,0 +1,52 @@
+import { InMemoryTransport } from "./inMemoryTransport.js";
+import { TransportRunnerBase, type TransportRunnerConfig } from "./base.js";
+import { type Server } from "../server.js";
+
+export type DryRunModeTestHelpers = {
+    logger: {
+        log(this: void, message: string): void;
+        error(this: void, message: string): void;
+    };
+};
+
+type DryRunModeRunnerConfig = TransportRunnerConfig & DryRunModeTestHelpers;
+
+export class DryRunModeRunner extends TransportRunnerBase {
+    private server: Server | undefined;
+    private consoleLogger: DryRunModeTestHelpers["logger"];
+
+    constructor({ logger, ...transportRunnerConfig }: DryRunModeRunnerConfig) {
+        super(transportRunnerConfig);
+        this.consoleLogger = logger;
+    }
+
+    override async start(): Promise<void> {
+        this.server = await this.setupServer();
+        const transport = new InMemoryTransport();
+
+        await this.server.connect(transport);
+        this.dumpConfig();
+        this.dumpTools();
+    }
+
+    override async closeTransport(): Promise<void> {
+        await this.server?.close();
+    }
+
+    private dumpConfig(): void {
+        this.consoleLogger.log("Configuration:");
+        this.consoleLogger.log(JSON.stringify(this.userConfig, null, 2));
+    }
+
+    private dumpTools(): void {
+        const tools =
+            this.server?.tools
+                .filter((tool) => tool.isEnabled())
+                .map((tool) => ({
+                    name: tool.name,
+                    category: tool.category,
+                })) ?? [];
+        this.consoleLogger.log("Enabled tools:");
+        this.consoleLogger.log(JSON.stringify(tools, null, 2));
+    }
+}
diff --git a/src/transports/inMemoryTransport.ts b/src/transports/inMemoryTransport.ts
diff --git a/tests/e2e/cli.test.ts b/tests/e2e/cli.test.ts
@@ -0,0 +1,30 @@
+import path from "path";
+import { execFile } from "child_process";
+import { promisify } from "util";
+import { describe, expect, it } from "vitest";
+import packageJson from "../../package.json" with { type: "json" };
+
+const execFileAsync = promisify(execFile);
+const CLI_PATH = path.join(import.meta.dirname, "..", "..", "dist", "index.js");
+
+describe("CLI entrypoint", () => {
+    it("should handle version request", async () => {
+        const { stdout, stderr } = await execFileAsync(process.execPath, [CLI_PATH, "--version"]);
+        expect(stdout).toContain(packageJson.version);
+        expect(stderr).toEqual("");
+    });
+
+    it("should handle help request", async () => {
+        const { stdout, stderr } = await execFileAsync(process.execPath, [CLI_PATH, "--help"]);
+        expect(stdout).toContain("For usage information refer to the README.md");
+        expect(stderr).toEqual("");
+    });
+
+    it("should handle dry run request", async () => {
+        const { stdout } = await execFileAsync(process.execPath, [CLI_PATH, "--dryRun"]);
+        expect(stdout).toContain("Configuration:");
+        expect(stdout).toContain("Enabled tools:");
+        // We don't do stderr assertions because in our CI, for docker-less env
+        // atlas local tools push message on stderr stream.
+    });
+});
diff --git a/tests/integration/helpers.ts b/tests/integration/helpers.ts
@@ -5,7 +5,7 @@ import { Server, type ServerOptions } from "../../src/server.js";
 import { Telemetry } from "../../src/telemetry/telemetry.js";
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { Client } from "@modelcontextprotocol/sdk/client/index.js";
-import { InMemoryTransport } from "./inMemoryTransport.js";
+import { InMemoryTransport } from "../../src/transports/inMemoryTransport.js";
 import { type UserConfig } from "../../src/common/config/userConfig.js";
 import { ResourceUpdatedNotificationSchema } from "@modelcontextprotocol/sdk/types.js";
 import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from "vitest";
diff --git a/tests/integration/tools/mongodb/mongodbTool.test.ts b/tests/integration/tools/mongodb/mongodbTool.test.ts
@@ -10,7 +10,7 @@ import { Session } from "../../../../src/common/session.js";
 import { CompositeLogger } from "../../../../src/common/logger.js";
 import { DeviceId } from "../../../../src/helpers/deviceId.js";
 import { ExportsManager } from "../../../../src/common/exportsManager.js";
-import { InMemoryTransport } from "../../inMemoryTransport.js";
+import { InMemoryTransport } from "../../../../src/transports/inMemoryTransport.js";
 import { Telemetry } from "../../../../src/telemetry/telemetry.js";
 import { Server } from "../../../../src/server.js";
 import { type ConnectionErrorHandler, connectionErrorHandler } from "../../../../src/common/connectionErrorHandler.js";
diff --git a/tests/unit/common/config.test.ts b/tests/unit/common/config.test.ts
@@ -25,81 +25,49 @@ function createEnvironment(): {
     };
 }
 
+// Expected hardcoded values (what we had before)
+const expectedDefaults = {
+    apiBaseUrl: "https://cloud.mongodb.com/",
+    logPath: getLogPath(),
+    exportsPath: getExportsPath(),
+    exportTimeoutMs: 5 * 60 * 1000, // 5 minutes
+    exportCleanupIntervalMs: 2 * 60 * 1000, // 2 minutes
+    disabledTools: [],
+    telemetry: "enabled",
+    readOnly: false,
+    indexCheck: false,
+    confirmationRequiredTools: [
+        "atlas-create-access-list",
+        "atlas-create-db-user",
+        "drop-database",
+        "drop-collection",
+        "delete-many",
+        "drop-index",
+    ],
+    transport: "stdio",
+    httpPort: 3000,
+    httpHost: "127.0.0.1",
+    loggers: ["disk", "mcp"],
+    idleTimeoutMs: 10 * 60 * 1000, // 10 minutes
+    notificationTimeoutMs: 9 * 60 * 1000, // 9 minutes
+    httpHeaders: {},
+    maxDocumentsPerQuery: 100,
+    maxBytesPerQuery: 16 * 1024 * 1024, // ~16 mb
+    atlasTemporaryDatabaseUserLifetimeMs: 4 * 60 * 60 * 1000, // 4 hours
+    voyageApiKey: "",
+    vectorSearchDimensions: 1024,
+    vectorSearchSimilarityFunction: "euclidean",
+    embeddingsValidation: true,
+    previewFeatures: [],
+    dryRun: false,
+};
+
 describe("config", () => {
     it("should generate defaults from UserConfigSchema that match expected values", () => {
-        // Expected hardcoded values (what we had before)
-        const expectedDefaults = {
-            apiBaseUrl: "https://cloud.mongodb.com/",
-            logPath: getLogPath(),
-            exportsPath: getExportsPath(),
-            exportTimeoutMs: 5 * 60 * 1000, // 5 minutes
-            exportCleanupIntervalMs: 2 * 60 * 1000, // 2 minutes
-            disabledTools: [],
-            telemetry: "enabled",
-            readOnly: false,
-            indexCheck: false,
-            confirmationRequiredTools: [
-                "atlas-create-access-list",
-                "atlas-create-db-user",
-                "drop-database",
-                "drop-collection",
-                "delete-many",
-                "drop-index",
-            ],
-            transport: "stdio",
-            httpPort: 3000,
-            httpHost: "127.0.0.1",
-            loggers: ["disk", "mcp"],
-            idleTimeoutMs: 10 * 60 * 1000, // 10 minutes
-            notificationTimeoutMs: 9 * 60 * 1000, // 9 minutes
-            httpHeaders: {},
-            maxDocumentsPerQuery: 100,
-            maxBytesPerQuery: 16 * 1024 * 1024, // ~16 mb
-            atlasTemporaryDatabaseUserLifetimeMs: 4 * 60 * 60 * 1000, // 4 hours
-            voyageApiKey: "",
-            vectorSearchDimensions: 1024,
-            vectorSearchSimilarityFunction: "euclidean",
-            embeddingsValidation: true,
-            previewFeatures: [],
-        };
         expect(UserConfigSchema.parse({})).toStrictEqual(expectedDefaults);
     });
 
     it("should generate defaults when no config sources are populated", () => {
-        const expectedDefaults = {
-            apiBaseUrl: "https://cloud.mongodb.com/",
-            logPath: getLogPath(),
-            exportsPath: getExportsPath(),
-            exportTimeoutMs: 5 * 60 * 1000, // 5 minutes
-            exportCleanupIntervalMs: 2 * 60 * 1000, // 2 minutes
-            disabledTools: [],
-            telemetry: "enabled",
-            readOnly: false,
-            indexCheck: false,
-            confirmationRequiredTools: [
-                "atlas-create-access-list",
-                "atlas-create-db-user",
-                "drop-database",
-                "drop-collection",
-                "delete-many",
-                "drop-index",
-            ],
-            transport: "stdio",
-            httpPort: 3000,
-            httpHost: "127.0.0.1",
-            loggers: ["disk", "mcp"],
-            idleTimeoutMs: 10 * 60 * 1000, // 10 minutes
-            notificationTimeoutMs: 9 * 60 * 1000, // 9 minutes
-            httpHeaders: {},
-            maxDocumentsPerQuery: 100,
-            maxBytesPerQuery: 16 * 1024 * 1024, // ~16 mb
-            atlasTemporaryDatabaseUserLifetimeMs: 4 * 60 * 60 * 1000, // 4 hours
-            voyageApiKey: "",
-            vectorSearchDimensions: 1024,
-            vectorSearchSimilarityFunction: "euclidean",
-            embeddingsValidation: true,
-            previewFeatures: [],
-        };
         expect(createUserConfig()).toStrictEqual(expectedDefaults);
     });
 
diff --git a/tests/unit/transports/dryModeRunner.test.ts b/tests/unit/transports/dryModeRunner.test.ts
@@ -0,0 +1,42 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { DryRunModeRunner, type DryRunModeTestHelpers } from "../../../src/transports/dryModeRunner.js";
+import { type UserConfig } from "../../../src/common/config/userConfig.js";
+import { type TransportRunnerConfig } from "../../../src/transports/base.js";
+import { defaultTestConfig } from "../../integration/helpers.js";
+
+describe("DryModeRunner", () => {
+    let loggerMock: DryRunModeTestHelpers["logger"];
+    let runnerConfig: TransportRunnerConfig;
+
+    beforeEach(() => {
+        loggerMock = {
+            log: vi.fn(),
+            error: vi.fn(),
+        };
+        runnerConfig = {
+            userConfig: defaultTestConfig,
+        } as TransportRunnerConfig;
+    });
+
+    afterEach(() => {
+        vi.clearAllMocks();
+    });
+
+    it.each([{ transport: "http", httpHost: "127.0.0.1", httpPort: "3001" }, { transport: "stdio" }] as Array<
+        Partial<UserConfig>
+    >)("should handle dry run request for transport - $transport", async (partialConfig) => {
+        runnerConfig.userConfig = {
+            ...runnerConfig.userConfig,
+            ...partialConfig,
+            dryRun: true,
+        };
+        const runner = new DryRunModeRunner({ logger: loggerMock, ...runnerConfig });
+        await runner.start();
+        expect(loggerMock.log).toHaveBeenNthCalledWith(1, "Configuration:");
+        expect(loggerMock.log).toHaveBeenNthCalledWith(2, JSON.stringify(runnerConfig.userConfig, null, 2));
+        expect(loggerMock.log).toHaveBeenNthCalledWith(3, "Enabled tools:");
+        expect(loggerMock.log).toHaveBeenNthCalledWith(4, expect.stringContaining('"name": "connect"'));
+        // Because switch-connection is not enabled by default
+        expect(loggerMock.log).toHaveBeenNthCalledWith(4, expect.not.stringContaining('"name": "switch-connection"'));
+    });
+});
