hypothesis-graphql 0.8.1

Hypothesis strategies for GraphQL schemas and queries

Hypothesis strategies for GraphQL schemas, queries and data.

NOTE This package is experimental, some features are not supported yet.

Usage

There are a few strategies for different use cases.

1. Schema generation - hypothesis_graphql.strategies.schemas()

2. Query - hypothesis_graphql.strategies.queries(schema).

3. Mutation - hypothesis_graphql.strategies.mutations(schema).

Lets take this schema as an example:

type Book {
  title: String
  author: Author
}

type Author {
  name: String
  books: [Book]
}

type Query {
  getBooks: [Book]
  getAuthors: [Author]
}

type Mutation {
  addBook(title: String!, author: String!): Book!
  addAuthor(name: String!): Author!
}

Then strategies might be used in this way:

from hypothesis import given
from hypothesis_graphql import strategies as gql_st

SCHEMA = "..."  # the one above


@given(gql_st.queries(SCHEMA))
def test_query(query):
    ...
    # This query might be generated:
    #
    # query {
    #   getBooks {
    #     title
    #   }
    # }


@given(gql_st.mutations(SCHEMA))
def test_mutation(mutation):
    ...
    # This mutation might be generated:
    #
    # mutation {
    #   addBook(title: "H4Z\u7869", author: "\u00d2"){
    #     title
    #   }
    # }

Customization

To restrict the set of fields in generated operations use the fields argument:

@given(gql_st.queries(SCHEMA, fields=["getAuthors"]))
def test_query(query):
    # Only `getAuthors` will be generated
    ...

It is also possible to generate custom scalars. For example, Date:

from hypothesis import strategies as st, given
from hypothesis_graphql import strategies as gql_st, nodes

SCHEMA = """
scalar Date

type Query {
  getByDate(created: Date!): Int
}
"""


@given(
    gql_st.queries(
        SCHEMA,
        custom_scalars={
            # Standard scalars work out of the box, for custom ones you need
            # to pass custom strategies that generate proper AST nodes
            "Date": st.dates().map(nodes.String)
        },
    )
)
def test_query(query):
    # Example:
    #
    #  { getByDate(created: "2000-01-01") }
    #
    ...

The hypothesis_graphql.nodes module includes a few helpers to generate various node types:

• String -> graphql.StringValueNode

• Float -> graphql.FloatValueNode

• Int -> graphql.IntValueNode

• Object -> graphql.ObjectValueNode

• List -> graphql.ListValueNode

• Boolean -> graphql.BooleanValueNode

• Enum -> graphql.EnumValueNode

• Null -> graphql.NullValueNode (a constant, not a function)

They exist because classes like graphql.StringValueNode can’t be directly used in map calls due to kwarg-only arguments.