Testing

The GraphiQL playground integrated with Strawberry available at http://localhost:8000/graphql (if you run the schema with strawberry server) can be a good place to start testing your queries and mutations. However, at some point, while you are developing your application (or even before if you are practising TDD), you may want to create some automated tests.

We can use the Strawberry schema object we defined in the Getting Started tutorial to run our first test:

def test_query():
    query = """
        query TestQuery($title: String!) {
            books(title: $title) {
                title
                author
            }
        }
    """

    result = schema.execute_sync(
        query,
        variable_values={"title": "The Great Gatsby"},
    )

    assert result.errors is None
    assert result.data["books"] == [
        {
            "title": "The Great Gatsby",
            "author": "F. Scott Fitzgerald",
        }
    ]

This test_query example:

1. defines the query we will test against; it accepts one argument, title, as input

2. executes the query and assigns the result to a result variable

3. asserts that the result is what we are expecting: nothing in errors and our desired book in data

As you may have noticed, we explicitly defined the query variable title, and we passed it separately with the variable_values argument, but we could have directly hardcoded the title in the query string instead. We did this on purpose because usually the query’s arguments will be dynamic and, as we want to test our application as close to production as possible, it wouldn’t make much sense to hardcode the variables in the query.

Testing Async

Since Strawberry supports async, tests can also be written to be async:

@pytest.mark.asyncio
async def test_query_async():
    ...

    resp = await schema.execute(query, variable_values={"title": "The Great Gatsby"})

    ...

Testing Mutations

We can also write a test for our addBook Mutation example:

@pytest.mark.asyncio
async def test_mutation():
    mutation = """
        mutation TestMutation($title: String!, $author: String!) {
            addBook(title: $title, author: $author) {
                title
            }
        }
    """

    resp = await schema.execute(
        mutation,
        variable_values={
            "title": "The Little Prince",
            "author": "Antoine de Saint-Exupéry",
        },
    )

    assert resp.errors is None
    assert resp.data["addBook"] == {
        "title": "The Little Prince",
    }

Testing Subscriptions

And finally, a test for our count Subscription:

import asyncio
import pytest
import strawberry


@strawberry.type
class Subscription:
    @strawberry.subscription
    async def count(self, target: int = 100) -> int:
        for i in range(target):
            yield i
            await asyncio.sleep(0.5)


@strawberry.type
class Query:
    @strawberry.field
    def hello() -> str:
        return "world"


schema = strawberry.Schema(query=Query, subscription=Subscription)


@pytest.mark.asyncio
async def test_subscription():
    query = """
    	subscription {
        	count(target: 3)
    	}
    """

    sub = await schema.subscribe(query)

    index = 0
    async for result in sub:
        assert not result.errors
        assert result.data == {"count": index}

        index += 1

As you can see testing Subscriptions is a bit more complicated because we want to check the result of each individual result.