refactor(NODE-2992): clean up server selection logic runner (#3201)

test/unit/assorted/server_selection.spec.test.ts

@@ -0,0 +1,36 @@
+import { join } from 'path';
+
+import {
+  collectServerSelectionLogicTests,
+  runServerSelectionLogicTest
+} from './server_selection_logic_spec_utils';
+
+describe('Server Selection Logic (spec)', function () {
+  beforeEach(function () {
+    if (this.currentTest.title.match(/Possible/)) {
+      this.currentTest.skipReason = 'Nodejs driver does not support PossiblePrimary';
+      this.skip();
+    }
+
+    if (this.currentTest.title.match(/nearest_multiple/i)) {
+      this.currentTest.skipReason = 'TODO(NODE-4188): localThresholdMS should default to 15ms';
+      this.skip();
+    }
+  });
+
+  const selectionSpecDir = join(__dirname, '../../spec/server-selection/server_selection');
+  const serverSelectionLogicTests = collectServerSelectionLogicTests(selectionSpecDir);
+  for (const topologyType of Object.keys(serverSelectionLogicTests)) {
+    describe(topologyType, function () {
+      for (const subType of Object.keys(serverSelectionLogicTests[topologyType])) {
+        describe(subType, function () {
+          for (const test of serverSelectionLogicTests[topologyType][subType]) {
+            it(test.name, function () {
+              runServerSelectionLogicTest(test);
+            });
+          }
+        });
+      }
+    });
+  }
+});

test/unit/assorted/server_selection_logic_spec_utils.ts

@@ -0,0 +1,155 @@
+import { Document, EJSON } from 'bson';
+import { expect } from 'chai';
+import { readdirSync, readFileSync, statSync } from 'fs';
+import { basename, extname, join } from 'path';
+
+import {
+  ReadPreference,
+  ReadPreferenceMode,
+  ReadPreferenceOptions
+} from '../../../src/read_preference';
+import { ServerType, TopologyType } from '../../../src/sdam/common';
+import { ServerDescription, TagSet } from '../../../src/sdam/server_description';
+import {
+  readPreferenceServerSelector,
+  writableServerSelector
+} from '../../../src/sdam/server_selection';
+import { TopologyDescription } from '../../../src/sdam/topology_description';
+import { serverDescriptionFromDefinition } from './server_selection_spec_helper';
+
+interface ServerSelectionLogicTestServer {
+  address: string;
+  avg_rtt_ms: number;
+  type: ServerType;
+  tags?: TagSet;
+}
+interface ServerSelectionLogicTest {
+  topology_description: {
+    type: TopologyType;
+    servers: ServerSelectionLogicTestServer[];
+  };
+  operation: 'read' | 'write';
+  read_preference: {
+    mode: ReadPreferenceMode;
+    tag_sets?: TagSet[];
+  };
+  /**
+   * The spec says we should confirm the list of suitable servers in addition to the list of
+   * servers in the latency window, if possible.  We apply the latency window inside the
+   * selector so for Node this is not possible.
+   * https://github.com/mongodb/specifications/tree/master/source/server-selection/tests#server-selection-logic-tests
+   */
+  suitable_servers: never;
+  in_latency_window: ServerSelectionLogicTestServer[];
+}
+
+function readPreferenceFromDefinition(definition) {
+  const mode = definition.mode
+    ? definition.mode.charAt(0).toLowerCase() + definition.mode.slice(1)
+    : 'primary';
+
+  const options: ReadPreferenceOptions = {};
+  if (typeof definition.maxStalenessSeconds !== 'undefined')
+    options.maxStalenessSeconds = definition.maxStalenessSeconds;
+  const tags = definition.tag_sets ?? [];
+
+  return new ReadPreference(mode, tags, options);
+}
+
+/**
+ * Compares two server descriptions and compares all fields that are present
+ * in the yaml spec tests.
+ */
+function compareServerDescriptions(s1: ServerDescription, s2: ServerDescription) {
+  expect(s1.address).to.equal(s2.address);
+  expect(s1.roundTripTime).to.equal(s2.roundTripTime);
+  expect(s1.type).to.equal(s2.type);
+  expect(s1.tags).to.deep.equal(s2.tags);
+}
+
+function serverDescriptionsToMap(
+  descriptions: ServerDescription[]
+): Map<string, ServerDescription> {
+  const descriptionMap = new Map<string, ServerDescription>();
+
+  for (const description of descriptions) {
+    descriptionMap.set(description.address, description);
+  }
+
+  return descriptionMap;
+}
+
+/**
+ * Executes a server selection logic test
+ * @see https://github.com/mongodb/specifications/tree/master/source/server-selection/tests#server-selection-logic-tests
+ */
+export function runServerSelectionLogicTest(testDefinition: ServerSelectionLogicTest) {
+  const allHosts = testDefinition.topology_description.servers.map(({ address }) => address);
+  const serversInTopology = testDefinition.topology_description.servers.map(s =>
+    serverDescriptionFromDefinition(s, allHosts)
+  );
+  const serverDescriptions = serverDescriptionsToMap(serversInTopology);
+  const topologyDescription = new TopologyDescription(
+    testDefinition.topology_description.type,
+    serverDescriptions
+  );
+  const expectedServers = serverDescriptionsToMap(
+    testDefinition.in_latency_window.map(s => serverDescriptionFromDefinition(s))
+  );
+
+  let selector;
+  if (testDefinition.operation === 'write') {
+    selector = writableServerSelector();
+  } else if (testDefinition.operation === 'read' || testDefinition.read_preference) {
+    const readPreference = readPreferenceFromDefinition(testDefinition.read_preference);
+    selector = readPreferenceServerSelector(readPreference);
+  } else {
+    expect.fail('test operation was neither read nor write, and no read preference was provided.');
+  }
+
+  const result = selector(topologyDescription, serversInTopology);
+
+  expect(result.length).to.equal(expectedServers.size);
+
+  for (const server of result) {
+    const expectedServer = expectedServers.get(server.address);
+    expect(expectedServer).to.exist;
+    compareServerDescriptions(server, expectedServer);
+    expectedServers.delete(server.address);
+  }
+
+  expect(expectedServers.size).to.equal(0);
+}
+
+/**
+ * reads in the server selection logic tests from the provided directory
+ */
+export function collectServerSelectionLogicTests(specDir) {
+  const testTypes = readdirSync(specDir).filter(d => statSync(join(specDir, d)).isDirectory());
+
+  const tests = {};
+  for (const testType of testTypes) {
+    const testsOfType = readdirSync(join(specDir, testType)).filter(d =>
+      statSync(join(specDir, testType, d)).isDirectory()
+    );
+    const result = {};
+    for (const subType of testsOfType) {
+      result[subType] = readdirSync(join(specDir, testType, subType))
+        .filter(f => extname(f) === '.json')
+        .map(f => {
+          const fileContents = readFileSync(join(specDir, testType, subType, f), {
+            encoding: 'utf-8'
+          });
+          const test = EJSON.parse(fileContents, { relaxed: true }) as unknown as Document;
+          test.name = basename(f, '.json');
+          test.type = testType;
+          test.subType = subType;
+          return test;
+        });
+    }
+
+    tests[testType] = result;
+  }
+
+  return tests;
+}

test/unit/assorted/server_selection_spec_helper.js

@@ -132,6 +132,10 @@ function executeServerSelectionTest(testDefinition, testDone) {
         if (testDefinition.error) return done();
         return done(e);
       }
+    } else {
+      return done(
+        new Error('received neither read nor write, and did not receive a read preference')
+      );
     }
 
     // expectations
@@ -196,4 +200,4 @@ function executeServerSelectionTest(testDefinition, testDone) {
   });
 }
 
-module.exports = { executeServerSelectionTest };
+module.exports = { executeServerSelectionTest, serverDescriptionFromDefinition };