chore: add some extra log level validations (#489)

Author: nirinchev

src/common/logger.ts

@@ -250,7 +250,7 @@ export class DiskLogger extends LoggerBase<{ initialized: [] }> {
 }
 
 export class McpLogger extends LoggerBase {
-    private static readonly LOG_LEVELS: LogLevel[] = [
+    public static readonly LOG_LEVELS: LogLevel[] = [
         "debug",
         "info",
         "notice",
@@ -259,7 +259,7 @@ export class McpLogger extends LoggerBase {
         "critical",
         "alert",
         "emergency",
-    ];
+    ] as const;
 
     public constructor(private readonly server: Server) {
         super();

src/server.ts

@@ -5,7 +5,7 @@ import { AtlasTools } from "./tools/atlas/tools.js";
 import { MongoDbTools } from "./tools/mongodb/tools.js";
 import { Resources } from "./resources/resources.js";
 import type { LogLevel } from "./common/logger.js";
-import { LogId } from "./common/logger.js";
+import { LogId, McpLogger } from "./common/logger.js";
 import type { Telemetry } from "./telemetry/telemetry.js";
 import type { UserConfig } from "./common/config.js";
 import { type ServerEvent } from "./telemetry/types.js";
@@ -107,6 +107,10 @@ export class Server {
         });
 
         this.mcpServer.server.setRequestHandler(SetLevelRequestSchema, ({ params }) => {
+            if (!McpLogger.LOG_LEVELS.includes(params.level)) {
+                throw new Error(`Invalid log level: ${params.level}`);
+            }
+
             this._mcpLogLevel = params.level;
             return {};
         });

tests/unit/logger.test.ts

@@ -7,6 +7,7 @@ import * as path from "path";
 import * as fs from "fs/promises";
 import { once } from "events";
 import type { Server } from "../../src/server.js";
+import { LoggingMessageNotificationSchema } from "@modelcontextprotocol/sdk/types.js";
 
 describe("Logger", () => {
     let consoleErrorSpy: MockInstance<typeof console.error>;
@@ -332,5 +333,9 @@ describe("Logger", () => {
             expect(mcpLoggerSpy).toHaveBeenCalledTimes(2);
             expect(getLastMcpLogMessage()).toContain("Alert message");
         });
+
+        it("MCPLogger.LOG_LEVELS contains all possible levels", () => {
+            expect(McpLogger.LOG_LEVELS).toEqual(LoggingMessageNotificationSchema.shape.params.shape.level.options);
+        });
     });
 });