test(NODE-3358): Command monitoring objects hold internal state references (#2860)

Author: W-A-James

test/functional/apm.test.js

@@ -659,41 +659,50 @@ describe('APM', function () {
     }
   });
 
-  // NODE-1502
-  it('should not allow mutation of internal state from commands returned by event monitoring', function () {
-    const started = [];
-    const succeeded = [];
-    const client = this.configuration.newClient(
-      { writeConcern: { w: 1 } },
-      { maxPoolSize: 1, monitorCommands: true }
-    );
-    client.on('commandStarted', filterForCommands('insert', started));
-    client.on('commandSucceeded', filterForCommands('insert', succeeded));
-    let documentToInsert = { a: { b: 1 } };
-    return client
-      .connect()
-      .then(client => {
-        const db = client.db(this.configuration.db);
-        return db.collection('apm_test').insertOne(documentToInsert);
-      })
-      .then(r => {
-        expect(r).to.have.property('insertedId').that.is.an('object');
-        expect(started).to.have.lengthOf(1);
-        // Check if contents of returned document are equal to document inserted (by value)
-        expect(documentToInsert).to.deep.equal(started[0].command.documents[0]);
-        // Check if the returned document is a clone of the original. This confirms that the
-        // reference is not the same.
-        expect(documentToInsert !== started[0].command.documents[0]).to.equal(true);
-        expect(documentToInsert.a !== started[0].command.documents[0].a).to.equal(true);
-
-        started[0].command.documents[0].a.b = 2;
-        expect(documentToInsert.a.b).to.equal(1);
-
-        expect(started[0].commandName).to.equal('insert');
-        expect(started[0].command.insert).to.equal('apm_test');
-        expect(succeeded).to.have.lengthOf(1);
-        return client.close();
-      });
+  describe('Internal state references', function () {
+    let client;
+    beforeEach(function () {
+      client = this.configuration.newClient(
+        { writeConcern: { w: 1 } },
+        { maxPoolSize: 1, monitorCommands: true }
+      );
+    });
+
+    afterEach(function (done) {
+      client.close(done);
+    });
+
+    // NODE-1502
+    it('should not allow mutation of internal state from commands returned by event monitoring', function () {
+      const started = [];
+      const succeeded = [];
+      client.on('commandStarted', filterForCommands('insert', started));
+      client.on('commandSucceeded', filterForCommands('insert', succeeded));
+      let documentToInsert = { a: { b: 1 } };
+      return client
+        .connect()
+        .then(client => {
+          const db = client.db(this.configuration.db);
+          return db.collection('apm_test').insertOne(documentToInsert);
+        })
+        .then(r => {
+          expect(r).to.have.property('insertedId').that.is.an('object');
+          expect(started).to.have.lengthOf(1);
+          // Check if contents of returned document are equal to document inserted (by value)
+          expect(documentToInsert).to.deep.equal(started[0].command.documents[0]);
+          // Check if the returned document is a clone of the original. This confirms that the
+          // reference is not the same.
+          expect(documentToInsert !== started[0].command.documents[0]).to.equal(true);
+          expect(documentToInsert.a !== started[0].command.documents[0].a).to.equal(true);
+
+          started[0].command.documents[0].a.b = 2;
+          expect(documentToInsert.a.b).to.equal(1);
+
+          expect(started[0].commandName).to.equal('insert');
+          expect(started[0].command.insert).to.equal('apm_test');
+          expect(succeeded).to.have.lengthOf(1);
+        });
+    });
   });
 
   describe('command monitoring spec tests', function () {