test(NODE-3719): fix max staleness test to assert against correct set and other clean up (#3116)

Author: dariakp

…e-step-down/connections_stepdown.test.js …nections_survive_step_down.prose.test.jstest/integration/connections-survive-step-down/connections_stepdown.test.js renamed to test/integration/connections-survive-step-down/connections_survive_step_down.prose.test.js test/integration/connections-survive-step-down/connections_stepdown.test.js renamed to test/integration/connections-survive-step-down/connections_survive_step_down.prose.test.js

@@ -25,8 +25,9 @@ function expectPoolWasNotCleared(initialCount) {
 }
 
 // TODO: NODE-3819: Unskip flaky MacOS tests.
+// TODO: NODE-3903: check events as specified in the corresponding prose test description
 const maybeDescribe = process.platform === 'darwin' ? describe.skip : describe;
-maybeDescribe('Connections survive primary step down', function () {
+maybeDescribe('Connections survive primary step down - prose', function () {
   let client;
   let checkClient;
   let db;

test/unit/assorted/max_staleness.spec.test.js

@@ -47,11 +47,8 @@ describe('Max Staleness (spec)', function () {
   Object.keys(specTests).forEach(specTestName => {
     describe(specTestName, () => {
       specTests[specTestName].forEach(testData => {
-        it(testData.description, {
-          metadata: { requires: { topology: 'single' } },
-          test: function (done) {
-            executeServerSelectionTest(testData, { checkLatencyWindow: false }, done);
-          }
+        it(testData.description, function (done) {
+          executeServerSelectionTest(testData, done);
         });
       });
     });

test/unit/assorted/server_selection.spec.test.js

@@ -63,18 +63,7 @@ describe('Server Selection (spec)', function () {
             const maybeIt = test.name.match(/Possible/) ? it.skip : it;
 
             maybeIt(test.name, function (done) {
-              executeServerSelectionTest(test, { checkLatencyWindow: false }, done);
-            });
-          });
-        });
-
-        describe(subType + ' (within latency window)', function () {
-          specTests[topologyType][subType].forEach(test => {
-            // NOTE: node does not support PossiblePrimary
-            const maybeIt = test.name.match(/Possible/) ? it.skip : it;
-
-            maybeIt(test.name, function (done) {
-              executeServerSelectionTest(test, { checkLatencyWindow: true }, done);
+              executeServerSelectionTest(test, done);
             });
           });
         });

test/unit/assorted/server_selection_spec_helper.js

@@ -7,10 +7,7 @@ const { MongoServerSelectionError } = require('../../../src/error');
 const ServerSelectors = require('../../../src/sdam/server_selection');
 
 const sinon = require('sinon');
-const chai = require('chai');
-
-const expect = chai.expect;
-chai.use(require('chai-subset'));
+const { expect } = require('chai');
 
 function serverDescriptionFromDefinition(definition, hosts) {
   hosts = hosts || [];
@@ -82,7 +79,7 @@ function readPreferenceFromDefinition(definition) {
   return new ReadPreference(mode, tags, options);
 }
 
-function executeServerSelectionTest(testDefinition, options, testDone) {
+function executeServerSelectionTest(testDefinition, testDone) {
   const topologyDescription = testDefinition.topology_description;
   const seedData = topologyDescription.servers.reduce(
     (result, seed) => {
@@ -140,15 +137,9 @@ function executeServerSelectionTest(testDefinition, options, testDone) {
     // expectations
     let expectedServers;
     if (!testDefinition.error) {
-      if (options.checkLatencyWindow) {
-        expectedServers = testDefinition.in_latency_window.map(s =>
-          serverDescriptionFromDefinition(s)
-        );
-      } else {
-        expectedServers = testDefinition.suitable_servers.map(s =>
-          serverDescriptionFromDefinition(s)
-        );
-      }
+      expectedServers = testDefinition.in_latency_window.map(s =>
+        serverDescriptionFromDefinition(s)
+      );
     }
 
     // default to serverSelectionTimeoutMS of `100` for unit tests
@@ -183,7 +174,20 @@ function executeServerSelectionTest(testDefinition, options, testDone) {
           return done(new Error('No suitable servers found!'));
         }
 
-        expect(selectedServerDescription).to.include.containSubset(expectedServerArray[0]);
+        if (expectedServerArray.length > 1) {
+          return done(new Error('This test does not support multiple expected servers'));
+        }
+
+        for (const [prop, value] of Object.entries(expectedServerArray[0])) {
+          if (prop === 'hosts') {
+            // we dynamically modify this prop during sever selection
+            continue;
+          }
+          expect(selectedServerDescription[prop]).to.deep.equal(
+            value,
+            `Mismatched selected server "${prop}"`
+          );
+        }
         done();
       } catch (e) {
         done(e);