roughly added estimated document count (#32)

Added support for the `estimatedDocumentCount` command; shouldn't need any further updates

Author: toptobes

src/data-api/collection.ts

@@ -1015,6 +1015,29 @@ export class Collection<Schema extends SomeDoc = SomeDoc> {
     return resp.status?.count;
   }
 
+  /**
+   * Gets an estimate of the count of documents in a collection.
+   *
+   * This operation is faster than {@link Collection.countDocuments} but may not be as accurate, and doesn't
+   * accept a filter. Unlike the former, **It can handle more than 1000 documents.**
+   *
+   * @remarks
+   * This gives a very rough estimate of the number of documents in the collection. It is not guaranteed to be
+   * accurate, and should not be used as a source of truth for the number of documents in the collection.
+   *
+   * @param options - The options for this operation.
+   *
+   * @returns The estimated number of documents in the collection
+   */
+  public async estimatedDocumentCount(options?: WithTimeout): Promise<number> {
+    const command = {
+      estimatedDocumentCount: {},
+    };
+
+    const resp = await this._httpClient.executeCommand(command, options);
+    return resp.status?.count;
+  }
+
   /**
    * Atomically finds a single document in the collection and replaces it.
    *

tests/integration/data-api/collection/estimated-document-count.test.ts

@@ -0,0 +1,28 @@
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// noinspection DuplicatedCode
+
+import { Collection } from '@/src/data-api';
+import { initTestObjects } from '@/tests/fixtures';
+import assert from 'assert';
+
+describe('integration.data-api.collection.estimated-document-count', () => {
+  let collection: Collection;
+
+  before(async function () {
+    [, , collection] = await initTestObjects(this);
+  });
+
+  it('roughly works', async () => {
+    const resp = await collection.estimatedDocumentCount();
+    assert.ok(typeof <any>resp === 'number');
+    assert.ok(resp >= 0);
+  });
+});