@shopify/graphql-testing

@shopify/graphql-testing

This package provides utilities to help in the following testing scenarios:

1. Testing a GraphQL operation with mock data
2. Testing the state of your application before/after all the GraphQL operations resolve

Installation

$ yarn add @shopify/graphql-testing

Usage

The default utility exported by this library is createGraphQLFactory. This factory accepts an optional options argument that allows you to pass a unionOrIntersectionTypes array and/ or additional cacheOptions that will be used to construct an Apollo in-memory cache.

const createGraphQL = createGraphQLFactory({
  unionOrIntersectionTypes: [],
});

The resulting function can be used to create a GraphQL controller that tracks and resolves GraphQL operations according to the mocks you supply. The mock you provide should be an object where the keys are operation names, and the values are either an object to return as data for that operation, or a function that takes a GraphQLRequest and returns suitable data. Alternatively, the mock can be a function that accepts a GraphQLRequest and returns suitable mock data.

const graphQL = createGraphQL({
  Pet: ({variables: {id}}) => ({pet: {id, name: 'Garfield'}}),
  Pets: () => ({pets: []}),
});

The call to the function returned by createGraphQLFactory (createGraphQL in the example above) creates a GraphQL instance, which is described in detail below.

GraphQL

The following method and properties are available on the GraphQL object:

resolveAll()

By default, the mock client will hold all the graphQL operations triggered by your application in a pending state. To resolve all pending graphQL operations, call graphQL.resolveAll(), which returns a promise that resolves once all the operations have completed.

await graphQL.resolveAll();

You can also pass a query or mutation option to resolveAll, which will filter the pending operations and only resolve the ones with a matching operation.

await graphQL.resolveAll({query: petQuery});

Note that, until a GraphQL operation has been resolved, it does not appear in the operations list described below.

wrap()

The wrap() method allows you to wrap all GraphQL resolutions in a function call. This can be useful when working with React components, which require that all operations that lead to state changes be wrapped in an act() call. The following example demonstrates using this with @shopify/react-testing:

const myComponent = mount(<MyComponent />);
const graphQL = createGraphQL(mocks);

graphQL.wrap(resolve => myComponent.act(resolve));

// Before, calling this could cause warnings about state updates happening outside
// of act(). Now, all GraphQL resolutions are safely wrapped in myComponent.act().
await graphQL.resolveAll();

#operations

graphQL.operations is a custom data structure that tracks all resolved GraphQL operations that the GraphQL controller has performed. This object has first(), last(), all(), and nth() methods, which allow you to inspect individual operations. All of these methods also accept an optional options argument, which allows you to narrow down the operations to specific queries or mutations:

const graphQL = createGraphQL(mocks);

// the very first operation, or undefined if no operations have been performed
graphQL.operations.first();

// the second last operation run with petQuery
graphQL.operations.nth(-2, {query: petQuery});

// the last operation of any kind
graphQL.operations.last();

// all mutations with this mutation
graphQL.operations.all({mutation: addPetMutation});

The query and mutation options both accept either a regular DocumentNode, or an async GraphQL component created with @shopify/react-graphql’s createAsyncQueryComponent function.

Matchers

This library provides a Jest matcher. To use this matcher, you’ll need to include @shopify/graphql-testing/matchers in your Jest setup file. The following matcher will then be available:

toHavePerformedGraphQLOperation(operation: GraphQLOperation, variables?: object)

This assertion should be run on a GraphQL object. It verifies that at least one operation matching the one you passed (either a DocumentNode or an async query component from @shopify/react-graphql) was completed. If you pass variables, this assertion will also ensure that at least one operation had matching variables. You only need to provide a subset of all variables, and the assertion argument can use any of Jest’s asymmetric matchers.

const graphQL = createGraphQL(mocks);

// perform something...

expect(graphQL).toHavePerformedGraphQLOperation(myQuery);
expect(graphQL).toHavePerformedGraphQLOperation(MyQueryComponent, {
  id: '123',
  first: expect.any(Number),
});