polish: add tests for expectPromise and expectEqualPromisesOrValues (#3655)

* polish: add tests for more testUtils

adds tests for expectPromise and expectEqualPromisesOrValues

* break out expectMatchingValues into another file

* apply review feedback

Author: yaacovCR

src/__testUtils__/__tests__/expectEqualPromisesOrValues-test.ts

@@ -0,0 +1,45 @@
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { expectEqualPromisesOrValues } from '../expectEqualPromisesOrValues';
+import { expectPromise } from '../expectPromise';
+
+describe('expectEqualPromisesOrValues', () => {
+  it('throws when given unequal values', () => {
+    expect(() => expectEqualPromisesOrValues([{}, {}, { test: 'test' }])).throw(
+      "expected { test: 'test' } to deeply equal {}",
+    );
+  });
+
+  it('does not throw when given equal values', () => {
+    const testValue = { test: 'test' };
+    expect(() =>
+      expectEqualPromisesOrValues([testValue, testValue, testValue]),
+    ).not.to.throw();
+  });
+
+  it('does not throw when given equal promises', async () => {
+    const testValue = Promise.resolve({ test: 'test' });
+
+    await expectPromise(
+      expectEqualPromisesOrValues([testValue, testValue, testValue]),
+    ).toResolve();
+  });
+
+  it('throws when given unequal promises', async () => {
+    await expectPromise(
+      expectEqualPromisesOrValues([
+        Promise.resolve({}),
+        Promise.resolve({}),
+        Promise.resolve({ test: 'test' }),
+      ]),
+    ).toRejectWith("expected { test: 'test' } to deeply equal {}");
+  });
+
+  it('throws when given equal values that are mixtures of values and promises', () => {
+    const testValue = { test: 'test' };
+    expect(() =>
+      expectEqualPromisesOrValues([testValue, Promise.resolve(testValue)]),
+    ).to.throw('Received an invalid mixture of promises and values.');
+  });
+});

src/__testUtils__/__tests__/expectMatchingValues-test.ts

@@ -0,0 +1,19 @@
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { expectEqualPromisesOrValues } from '../expectEqualPromisesOrValues';
+
+describe('expectMatchingValues', () => {
+  it('throws when given unequal values', () => {
+    expect(() => expectEqualPromisesOrValues([{}, {}, { test: 'test' }])).throw(
+      "expected { test: 'test' } to deeply equal {}",
+    );
+  });
+
+  it('does not throw when given equal values', () => {
+    const testValue = { test: 'test' };
+    expect(() =>
+      expectEqualPromisesOrValues([testValue, testValue, testValue]),
+    ).not.to.throw();
+  });
+});

src/__testUtils__/__tests__/expectPromise-test.ts

@@ -0,0 +1,53 @@
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { expectPromise } from '../expectPromise';
+
+describe('expectPromise', () => {
+  it('throws if passed a value', () => {
+    expect(() => expectPromise({})).to.throw(
+      "Expected a promise, received '{}'",
+    );
+  });
+
+  it('toResolve returns the resolved value', async () => {
+    const testValue = {};
+    const promise = Promise.resolve(testValue);
+    expect(await expectPromise(promise).toResolve()).to.equal(testValue);
+  });
+
+  it('toRejectWith throws if the promise does not reject', async () => {
+    try {
+      await expectPromise(Promise.resolve({})).toRejectWith(
+        'foo',
+      ); /* c8 ignore start */
+    } /* c8 ignore stop */ catch (err) {
+      expect(err.message).to.equal(
+        "Promise should have rejected with message 'foo', but resolved as '{}'",
+      );
+    }
+  });
+
+  it('toRejectWith throws if the promise rejects with the wrong reason', async () => {
+    try {
+      await expectPromise(Promise.reject(new Error('foo'))).toRejectWith(
+        'bar',
+      ); /* c8 ignore start */
+    } /* c8 ignore stop */ catch (err) {
+      expect(err.message).to.equal(
+        "expected Error: foo to have property 'message' of 'bar', but got 'foo'",
+      );
+    }
+  });
+
+  it('toRejectWith does not throw if the promise rejects with the right reason', async () => {
+    try {
+      await expectPromise(Promise.reject(new Error('foo'))).toRejectWith(
+        'foo',
+      ); /* c8 ignore start */
+    } catch (err) {
+      // Not reached.
+      expect.fail('promise threw unexpectedly');
+    } /* c8 ignore stop */
+  });
+});

src/__testUtils__/expectEqualPromisesOrValues.ts

@@ -0,0 +1,21 @@
+import { assert } from 'chai';
+
+import { isPromise } from '../jsutils/isPromise';
+import type { PromiseOrValue } from '../jsutils/PromiseOrValue';
+
+import { expectMatchingValues } from './expectMatchingValues';
+
+export function expectEqualPromisesOrValues<T>(
+  items: ReadonlyArray<PromiseOrValue<T>>,
+): PromiseOrValue<T> {
+  const [firstItem, ...remainingItems] = items;
+  if (isPromise(firstItem)) {
+    if (remainingItems.every(isPromise)) {
+      return Promise.all(items).then(expectMatchingValues);
+    }
+  } else if (remainingItems.every((item) => !isPromise(item))) {
+    return expectMatchingValues(items);
+  }
+
+  assert(false, 'Received an invalid mixture of promises and values.');
+}

src/__testUtils__/expectMatchingValues.ts

@@ -0,0 +1,9 @@
+import { expectJSON } from './expectJSON';
+
+export function expectMatchingValues<T>(values: ReadonlyArray<T>): T {
+  const [firstValue, ...remainingValues] = values;
+  for (const value of remainingValues) {
+    expectJSON(value).toDeepEqual(firstValue);
+  }
+  return firstValue;
+}

src/__testUtils__/expectPromise.ts

@@ -0,0 +1,38 @@
+import { assert, expect } from 'chai';
+
+import { inspect } from '../jsutils/inspect';
+import { isPromise } from '../jsutils/isPromise';
+
+export function expectPromise(maybePromise: unknown) {
+  assert(
+    isPromise(maybePromise),
+    `Expected a promise, received '${inspect(maybePromise)}'`,
+  );
+
+  return {
+    toResolve() {
+      return maybePromise;
+    },
+    async toRejectWith(message: string) {
+      let caughtError: Error | undefined;
+      let resolved;
+      let rejected = false;
+      try {
+        resolved = await maybePromise;
+      } catch (error) {
+        rejected = true;
+        caughtError = error;
+      }
+
+      assert(
+        rejected,
+        `Promise should have rejected with message '${message}', but resolved as '${inspect(
+          resolved,
+        )}'`,
+      );
+
+      expect(caughtError).to.be.an.instanceOf(Error);
+      expect(caughtError).to.have.property('message', message);
+    },
+  };
+}

src/execution/__tests__/subscribe-test.ts

@@ -1,7 +1,9 @@
 import { assert, expect } from 'chai';
 import { describe, it } from 'mocha';
 
+import { expectEqualPromisesOrValues } from '../../__testUtils__/expectEqualPromisesOrValues';
 import { expectJSON } from '../../__testUtils__/expectJSON';
+import { expectPromise } from '../../__testUtils__/expectPromise';
 import { resolveOnNextTick } from '../../__testUtils__/resolveOnNextTick';
 
 import { isAsyncIterable } from '../../jsutils/isAsyncIterable';
@@ -125,49 +127,6 @@ function createSubscription(pubsub: SimplePubSub<Email>) {
   return subscribe({ schema: emailSchema, document, rootValue: data });
 }
 
-// TODO: consider adding this method to testUtils (with tests)
-function expectPromise(maybePromise: unknown) {
-  assert(isPromise(maybePromise));
-
-  return {
-    toResolve() {
-      return maybePromise;
-    },
-    async toRejectWith(message: string) {
-      let caughtError: Error;
-
-      try {
-        /* c8 ignore next 2 */
-        await maybePromise;
-        expect.fail('promise should have thrown but did not');
-      } catch (error) {
-        caughtError = error;
-      }
-
-      expect(caughtError).to.be.an.instanceOf(Error);
-      expect(caughtError).to.have.property('message', message);
-    },
-  };
-}
-
-// TODO: consider adding this method to testUtils (with tests)
-function expectEqualPromisesOrValues<T>(
-  value1: PromiseOrValue<T>,
-  value2: PromiseOrValue<T>,
-): PromiseOrValue<T> {
-  if (isPromise(value1)) {
-    assert(isPromise(value2));
-    return Promise.all([value1, value2]).then((resolved) => {
-      expectJSON(resolved[1]).toDeepEqual(resolved[0]);
-      return resolved[0];
-    });
-  }
-
-  assert(!isPromise(value2));
-  expectJSON(value2).toDeepEqual(value1);
-  return value1;
-}
-
 const DummyQueryType = new GraphQLObjectType({
   name: 'Query',
   fields: {
@@ -195,10 +154,10 @@ function subscribeWithBadFn(
 function subscribeWithBadArgs(
   args: ExecutionArgs,
 ): PromiseOrValue<ExecutionResult | AsyncIterable<unknown>> {
-  return expectEqualPromisesOrValues(
+  return expectEqualPromisesOrValues([
     subscribe(args),
     createSourceEventStream(args),
-  );
+  ]);
 }
 
 /* eslint-disable @typescript-eslint/require-await */