Support integration tests

Integration tests are slower than unit tests because they rely on
a database connection, so we want the ability to run them separately
depending on our environment.

Jest allows us to define different config files.  By creating a `base`
config we can define all of the common settings between unit and
integration tests, and then customize for each type in the respective
extended configs.

In addition to configuration this begins to define define some hooks
so that we can eventually run these tests in parallel.  Unfortunately
there is a bug in the migration library we're using which prevents that
kind of parallel migration within a single database / across multiple
schemas.  We have an open PR with a patch for that bug[1].

[1] ThomWright/postgres-migrations#93

Issue #43 Support integration tests

Author: slifty

README.md

@@ -24,7 +24,14 @@ In order to run this software you need to set up a [Postgres 14](https://www.pos
   edit .env
   ```
 
-3. Run migrations
+3. Set up test environment variables
+
+  ```bash
+  cp .env.example .env.test
+  edit .env.test
+  ```
+
+4. Run migrations
 
   ```bash
   npm run migrate:dev

jest.config.js renamed to jest.config.base.js

@@ -6,6 +6,7 @@ module.exports = {
   },
   collectCoverageFrom: ["src/**/*.ts"],
   preset: 'ts-jest',
+  setupFiles: ['<rootDir>/src/test/setupEnv.ts'],
   testEnvironment: 'node',
   testPathIgnorePatterns: ["<rootDir>/dist/"],
   silent: true,

jest.config.int.js

@@ -0,0 +1,4 @@
+var config = require('./jest.config.base.js');
+config.testMatch = ['**/?(*.)+(int).(spec|test).[jt]s?(x)'];
+config.setupFilesAfterEnv = ["<rootDir>/src/test/integrationSuiteSetup.ts"];
+module.exports = config;

jest.config.unit.js

@@ -0,0 +1,3 @@
+var config = require('./jest.config.base.js');
+config.testMatch = ['**/?(*.)+(unit).(spec|test).[jt]s?(x)'];
+module.exports = config;

package.json

@@ -11,7 +11,9 @@
     "lint": "eslint ./src --ext .ts",
     "migrate": "node -r dotenv/config dist/scripts/migrate.js",
     "migrate:dev": "ts-node -r dotenv/config src/scripts/migrate.ts",
-    "test": "jest",
+    "test": "npm run test:unit && npm run test:integration",
+    "test:unit": "jest --config=jest.config.unit.js",
+    "test:integration": "jest --config=jest.config.int.js --runInBand",
     "start": "node dist/index.js",
     "start:dev": "ts-node src/index.ts"
   },

src/__tests__/canonicalFields.test.ts renamed to src/__tests__/canonicalFields.int.test.ts

@@ -1,14 +1,20 @@
 import request from 'supertest';
 import { app } from '../app';
+import {
+  prepareDatabaseForCurrentWorker,
+  cleanupDatabaseForCurrentWorker,
+} from '../test/utils';
 
 const agent = request.agent(app);
 
 describe('/canonicalFields', () => {
   describe('/', () => {
     it('should return HTTP Status Code 200 OK', async () => {
+      await prepareDatabaseForCurrentWorker();
       await agent
         .get('/canonicalFields')
         .expect(200);
+      await cleanupDatabaseForCurrentWorker();
     });
   });
 });

src/test/integrationSuiteSetup.ts

@@ -0,0 +1,5 @@
+import { db } from '../database';
+
+afterAll(async () => {
+  await db.close();
+});

src/test/setupEnv.ts

@@ -0,0 +1,3 @@
+import dotenv from 'dotenv';
+
+dotenv.config({ path: '.env.test' });

src/test/utils.ts

@@ -0,0 +1,40 @@
+import {
+  db,
+  migrate,
+} from '../database';
+
+const generateSchemaName = (workerId: string): string => `test_${workerId}`;
+
+const getSchemaNameForCurrentTestWorker = (): string => {
+  if (process.env.NODE_ENV !== 'test') {
+    throw new Error('You cannot get a test schema name outside of a test environment.');
+  }
+  if (process.env.JEST_WORKER_ID === undefined) {
+    throw new Error('You cannot get a test schema name if jest has not specified a worker ID.');
+  }
+  return generateSchemaName(process.env.JEST_WORKER_ID);
+};
+
+const createSchema = async (schemaName: string): Promise<void> => {
+  await db.query(`CREATE SCHEMA IF NOT EXISTS ${schemaName};`);
+};
+
+const setSchema = async (schemaName: string): Promise<void> => {
+  await db.query(`SET search_path TO ${schemaName};`);
+};
+
+const dropSchema = async (schemaName: string): Promise<void> => {
+  await db.query(`DROP SCHEMA ${schemaName} CASCADE;`);
+};
+
+export const prepareDatabaseForCurrentWorker = async (): Promise<void> => {
+  const schemaName = getSchemaNameForCurrentTestWorker();
+  await createSchema(schemaName);
+  await setSchema(schemaName);
+  await migrate();
+};
+
+export const cleanupDatabaseForCurrentWorker = async (): Promise<void> => {
+  const schemaName = getSchemaNameForCurrentTestWorker();
+  await dropSchema(schemaName);
+};