fix(tests): fix flakiness, again…

Turns out the real reason was that we had `begin`/`commit`s creating transactions in our kitchen sink SQL queries. Therefore the changes were not being rolled back appropriately. Turns out `begin`/`commit` does not compose.

The fix would involve simply removing `begin` and `commit` from `resources/kitchen-sink-data.sql` and `resources/kitchen-sink-schema.sql`, however we made a couple of other good changes in this commit trying to fix the problem.

resources/kitchen-sink-data.sql

@@ -1,4 +1,5 @@
-begin;
+-- We don’t have a `begin`/`commit` in here to let the users of this query
+-- control the data lifecycle.
 
 insert into c.person (id, name, email, about, created_at) values
   (1, 'John Smith', '[email protected]', null, null),
@@ -31,5 +32,3 @@ insert into c.compound_key (person_id_1, person_id_2, extra) values
   (2, 5, true),
   (2, 3, null),
   (4, 4, false);
-
-commit;

resources/kitchen-sink-schema.sql

@@ -1,8 +1,7 @@
-begin;
+-- We don’t have a `begin`/`commit` in here to let the users of this query
+-- control the data lifecycle.
 
-drop schema if exists a cascade;
-drop schema if exists b cascade;
-drop schema if exists c cascade;
+drop schema if exists a, b, c cascade;
 
 create schema a;
 create schema b;
@@ -108,5 +107,3 @@ create table b.types (
 --   b text not null,
 --   unique (a, b)
 -- );
-
-commit;

src/postgraphql/__tests__/postgraphqlIntegration-test.js

@@ -2,7 +2,7 @@ import { resolve as resolvePath } from 'path'
 import { readFile, readdirSync } from 'fs'
 import { GraphQLSchema, printSchema, graphql } from 'graphql'
 import { Inventory, Context } from '../../interface'
-import getTestPGClient from '../../postgres/__tests__/fixtures/getTestPGClient'
+import withPGClient from '../../postgres/__tests__/fixtures/withPGClient'
 import { introspectDatabase } from '../../postgres/introspection'
 import addPGCatalogToInventory from '../../postgres/inventory/addPGCatalogToInventory'
 import { createPGContext } from '../../postgres/inventory/pgContext'
@@ -20,8 +20,7 @@ const kitchenSinkData = new Promise((resolve, reject) => {
  */
 let schema1, schema2
 
-beforeAll(async () => {
-  const client = await getTestPGClient()
+beforeAll(withPGClient(async client => {
   const catalog = await introspectDatabase(client, ['a', 'b', 'c'])
 
   const inventory1 = new Inventory()
@@ -31,7 +30,7 @@ beforeAll(async () => {
   const inventory2 = new Inventory()
   addPGCatalogToInventory(inventory2, catalog, { renameIdToRowId: true })
   schema2 = createGraphqlSchema(inventory2, { nodeIdFieldName: 'id' })
-})
+}))
 
 test('schema', async () => {
   expect(printSchema(schema1)).toMatchSnapshot()
@@ -41,20 +40,20 @@ test('schema', async () => {
 const queriesDir = resolvePath(__dirname, 'fixtures/queries')
 
 for (const file of readdirSync(queriesDir)) {
-  test(`query ${file}`, async () => {
-    const query = await (new Promise((resolve, reject) => {
+  test(`query ${file}`, withPGClient(async client => {
+    const query = await new Promise((resolve, reject) => {
       readFile(resolvePath(queriesDir, file), (error, data) => {
         if (error) reject(error)
         else resolve(data.toString())
       })
-    }))
+    })
 
-    const client = await getTestPGClient()
     await client.query(await kitchenSinkData)
+
     const context = createPGContext(client)
 
     const result = await graphql(schema1, query, null, context)
 
     expect(result).toMatchSnapshot()
-  })
+  }))
 }

src/postgres/__tests__/fixtures/withPGClient.ts

@@ -0,0 +1,46 @@
+import { resolve as resolvePath } from 'path'
+import { readFile } from 'fs'
+import { Pool, Client } from 'pg'
+import minify = require('pg-minify')
+
+const pool = new Pool({
+  database: 'postgraphql_test',
+  port: 5432,
+  max: 15,
+  idleTimeoutMillis: 500,
+})
+
+const kitchenSinkSchema = new Promise<string>((resolve, reject) => {
+  readFile(resolvePath(__dirname, '../../../../resources/kitchen-sink-schema.sql'), (error, data) => {
+    if (error) reject(error)
+    else resolve(minify(data.toString()))
+  })
+})
+
+/**
+ * Takes a function implementation of a test, and provides it a Postgres
+ * client. The client will be connected from the pool at the start of the test,
+ * and released back at the end. All changes will be rolled back.
+ */
+export default function withPGClient (fn: (client: Client) => void | Promise<void>) {
+  return async () => {
+    // Connect a client from our pool and begin a transaction.
+    const client = await pool.connect()
+    await client.query('begin')
+    await client.query(await kitchenSinkSchema)
+
+    // Mock the query function.
+    client.query = jest.fn(client.query)
+
+    // Try to run our test, if it fails we still want to cleanup the client.
+    try {
+      await fn(client)
+    }
+    // Always rollback our changes and release the client, even if the test
+    // fails.
+    finally {
+      await client.query('rollback')
+      client.release()
+    }
+  }
+}

src/postgres/introspection/__tests__/introspectDatabase-test.js

@@ -1,4 +1,4 @@
-import getTestPGClient from '../../__tests__/fixtures/getTestPGClient'
+import withPGClient from '../../__tests__/fixtures/withPGClient'
 import createKitchenSinkPGSchema from '../../__tests__/fixtures/createKitchenSinkPGSchema'
 import introspectDatabase from '../introspectDatabase'
 
@@ -89,8 +89,7 @@ const format = catalog => ({
     })),
 })
 
-test('will get everything needed in an introspection', async () => {
-  const client = await getTestPGClient()
+test('will get everything needed in an introspection', withPGClient(async client => {
   expect(format(await introspectDatabase(client, ['a', 'b', 'c']))).toMatchSnapshot()
   expect(format(await introspectDatabase(client, ['a']))).toMatchSnapshot()
-})
+}))