chore: add integration tests for count (#78)

Author: nirinchev

eslint.config.js

@@ -30,6 +30,6 @@ export default defineConfig([
         // TODO: Configure tests and scripts to work with this.
         ignores: ["eslint.config.js", "jest.config.js", "tests/**/*.ts", "scripts/**/*.ts"],
     }),
-    globalIgnores(["node_modules", "dist", "src/common/atlas/openapi.d.ts"]),
+    globalIgnores(["node_modules", "dist", "src/common/atlas/openapi.d.ts", "coverage"]),
     eslintConfigPrettier,
 ]);

src/tools/mongodb/read/count.ts

@@ -30,7 +30,7 @@ export class CountTool extends MongoDBToolBase {
         return {
             content: [
                 {
-                    text: `Found ${count} documents in the collection \`${collection}\``,
+                    text: `Found ${count} documents in the collection "${collection}"`,
                     type: "text",
                 },
             ],

tests/integration/helpers.ts

@@ -13,6 +13,7 @@ interface ParameterInfo {
     name: string;
     type: string;
     description: string;
+    required: boolean;
 }
 
 type ToolInfo = Awaited<ReturnType<Client["listTools"]>>["tools"][number];
@@ -180,10 +181,16 @@ export function getParameters(tool: ToolInfo): ParameterInfo[] {
                 name: key,
                 type: typedValue.type,
                 description: typedValue.description,
+                required: (tool.inputSchema.required as string[])?.includes(key) ?? false,
             };
         });
 }
 
+export const dbOperationParameters: ParameterInfo[] = [
+    { name: "database", type: "string", description: "Database name", required: true },
+    { name: "collection", type: "string", description: "Collection name", required: true },
+];
+
 export function validateParameters(tool: ToolInfo, parameters: ParameterInfo[]): void {
     const toolParameters = getParameters(tool);
     expect(toolParameters).toHaveLength(parameters.length);

tests/integration/tools/mongodb/create/createCollection.test.ts

@@ -4,6 +4,7 @@ import {
     jestTestMCPClient,
     getResponseContent,
     validateParameters,
+    dbOperationParameters,
 } from "../../../helpers.js";
 import { toIncludeSameMembers } from "jest-extended";
 import { McpError } from "@modelcontextprotocol/sdk/types.js";
@@ -21,18 +22,7 @@ describe("createCollection tool", () => {
             "Creates a new collection in a database. If the database doesn't exist, it will be created automatically."
         );
 
-        validateParameters(listCollections, [
-            {
-                name: "database",
-                description: "Database name",
-                type: "string",
-            },
-            {
-                name: "collection",
-                description: "Collection name",
-                type: "string",
-            },
-        ]);
+        validateParameters(listCollections, dbOperationParameters);
     });
 
     describe("with invalid arguments", () => {

tests/integration/tools/mongodb/metadata/connect.test.ts

@@ -17,6 +17,7 @@ describe("Connect tool", () => {
                 name: "connectionStringOrClusterName",
                 description: "MongoDB connection string (in the mongodb:// or mongodb+srv:// format) or cluster name",
                 type: "string",
+                required: false,
             },
         ]);
     });

tests/integration/tools/mongodb/metadata/listCollections.test.ts

@@ -4,7 +4,6 @@ import {
     jestTestCluster,
     jestTestMCPClient,
     getResponseContent,
-    getParameters,
     validateParameters,
 } from "../../../helpers.js";
 import { toIncludeSameMembers } from "jest-extended";
@@ -20,7 +19,9 @@ describe("listCollections tool", () => {
         expect(listCollections).toBeDefined();
         expect(listCollections.description).toBe("List all collections for a given database");
 
-        validateParameters(listCollections, [{ name: "database", description: "Database name", type: "string" }]);
+        validateParameters(listCollections, [
+            { name: "database", description: "Database name", type: "string", required: true },
+        ]);
     });
 
     describe("with invalid arguments", () => {

tests/integration/tools/mongodb/read/count.test.ts

@@ -0,0 +1,118 @@
+import {
+    connect,
+    jestTestCluster,
+    jestTestMCPClient,
+    getResponseContent,
+    validateParameters,
+    dbOperationParameters,
+} from "../../../helpers.js";
+import { toIncludeSameMembers } from "jest-extended";
+import { McpError } from "@modelcontextprotocol/sdk/types.js";
+import { ObjectId } from "mongodb";
+
+describe("count tool", () => {
+    const client = jestTestMCPClient();
+    const cluster = jestTestCluster();
+
+    let randomDbName: string;
+    beforeEach(() => {
+        randomDbName = new ObjectId().toString();
+    });
+
+    it("should have correct metadata", async () => {
+        const { tools } = await client().listTools();
+        const listCollections = tools.find((tool) => tool.name === "count")!;
+        expect(listCollections).toBeDefined();
+        expect(listCollections.description).toBe("Gets the number of documents in a MongoDB collection");
+
+        validateParameters(listCollections, [
+            {
+                name: "query",
+                description:
+                    "The query filter to count documents. Matches the syntax of the filter argument of db.collection.count()",
+                type: "object",
+                required: false,
+            },
+            ...dbOperationParameters,
+        ]);
+    });
+
+    describe("with invalid arguments", () => {
+        const args = [
+            {},
+            { database: 123, collection: "bar" },
+            { foo: "bar", database: "test", collection: "bar" },
+            { collection: [], database: "test" },
+            { collection: "bar", database: "test", query: "{ $gt: { foo: 5 } }" },
+        ];
+        for (const arg of args) {
+            it(`throws a schema error for: ${JSON.stringify(arg)}`, async () => {
+                await connect(client(), cluster());
+                try {
+                    await client().callTool({ name: "count", arguments: arg });
+                    expect.fail("Expected an error to be thrown");
+                } catch (error) {
+                    expect(error).toBeInstanceOf(McpError);
+                    const mcpError = error as McpError;
+                    expect(mcpError.code).toEqual(-32602);
+                    expect(mcpError.message).toContain("Invalid arguments for tool count");
+                }
+            });
+        }
+    });
+
+    it("returns 0 when database doesn't exist", async () => {
+        await connect(client(), cluster());
+        const response = await client().callTool({
+            name: "count",
+            arguments: { database: "non-existent", collection: "foos" },
+        });
+        const content = getResponseContent(response.content);
+        expect(content).toEqual('Found 0 documents in the collection "foos"');
+    });
+
+    it("returns 0 when collection doesn't exist", async () => {
+        await connect(client(), cluster());
+        const mongoClient = cluster().getClient();
+        await mongoClient.db(randomDbName).collection("bar").insertOne({});
+        const response = await client().callTool({
+            name: "count",
+            arguments: { database: randomDbName, collection: "non-existent" },
+        });
+        const content = getResponseContent(response.content);
+        expect(content).toEqual('Found 0 documents in the collection "non-existent"');
+    });
+
+    describe("with existing database", () => {
+        beforeEach(async () => {
+            const mongoClient = cluster().getClient();
+            await mongoClient
+                .db(randomDbName)
+                .collection("foo")
+                .insertMany([
+                    { name: "Peter", age: 5 },
+                    { name: "Parker", age: 10 },
+                    { name: "George", age: 15 },
+                ]);
+        });
+
+        const testCases = [
+            { filter: undefined, expectedCount: 3 },
+            { filter: {}, expectedCount: 3 },
+            { filter: { age: { $lt: 15 } }, expectedCount: 2 },
+            { filter: { age: { $gt: 5 }, name: { $regex: "^P" } }, expectedCount: 1 },
+        ];
+        for (const testCase of testCases) {
+            it(`returns ${testCase.expectedCount} documents for filter ${JSON.stringify(testCase.filter)}`, async () => {
+                await connect(client(), cluster());
+                const response = await client().callTool({
+                    name: "count",
+                    arguments: { database: randomDbName, collection: "foo", query: testCase.filter },
+                });
+
+                const content = getResponseContent(response.content);
+                expect(content).toEqual(`Found ${testCase.expectedCount} documents in the collection "foo"`);
+            });
+        }
+    });
+});