Schema testing in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a GraphQL type for a User with an ID field.

GraphQL

type User { id: [1] }

Drag options to blanks, or click blank then click option'

AID!

BString

CInt

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of ID for unique identifiers.

Forgetting the exclamation mark to make the field required.

The ID! type is used for unique identifiers and the exclamation mark means it is required.

2fill in blank

medium

Complete the code to add a name field of type String to the User type.

GraphQL

type User { name: [1] }

Drag options to blanks, or click blank then click option'

AString!

BID

CBoolean

DInt

Attempts:

3 left

💡 Hint

Common Mistakes

Using ID instead of String for text fields.

Omitting the exclamation mark if the field is required.

The String! type means the name is a required string field.

3fill in blank

hard

Fix the error in the schema by completing the field type for age.

GraphQL

type User { age: [1] }

Drag options to blanks, or click blank then click option'

AString!

BBoolean

CID

DInt!

Attempts:

3 left

💡 Hint

Common Mistakes

Using String or Boolean for age.

Forgetting the exclamation mark for required fields.

The Int! type is used for required integer fields like age.

4fill in blank

hard

Fill both blanks to define a Query type with a user field returning a User by ID.

GraphQL

type Query { user(id: [1]): [2] }

Drag options to blanks, or click blank then click option'

AID!

BUser

CString

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of ID for the id argument.

Returning String or Boolean instead of User.

The user query takes a required ID! argument and returns a User type.

5fill in blank

hard

Fill all three blanks to define a Mutation type with createUser taking name and age and returning User.

GraphQL

type Mutation { createUser(name: [1], age: [2]): [3] }

Drag options to blanks, or click blank then click option'

AString!

BInt!

CUser

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using optional types instead of required with exclamation marks.

Returning Boolean instead of User.

The createUser mutation takes a required String! name and a required Int! age, and returns a User.

Practice

1. What is the main purpose of schema testing in GraphQL?

easy

A. To check the database connection

B. To test the speed of GraphQL queries

C. To verify that the GraphQL schema matches the expected structure and types

D. To validate user authentication tokens

Solution

1. Step 1: Understand schema testing purpose

   Schema testing ensures the GraphQL schema is correct and matches the design.

2. Step 2: Compare options to purpose

   Only verifying schema structure and types matches schema testing's goal.

3. Final Answer:

   To verify that the GraphQL schema matches the expected structure and types -> Option C

4. Quick Check:

   Schema testing = verify schema structure [OK]

Hint: Schema testing checks schema structure, not performance or auth [OK]

Common Mistakes:

• Confusing schema testing with performance testing
• Thinking schema testing checks database connections
• Assuming schema testing validates user authentication

2. Which of the following is the correct syntax to define a GraphQL schema type for a User with fields id (ID!) and name (String)?

easy

A. User { id: ID! name: String }

B. schema User { id: ID! name: String }

C. type User (id: ID!, name: String)

D. type User { id: ID! name: String }

Solution

1. Step 1: Recall GraphQL type syntax

   GraphQL types use the keyword type followed by name and curly braces with fields.

2. Step 2: Match syntax to options

   type User { id: ID! name: String } correctly uses type User { id: ID! name: String }. Others misuse keywords or punctuation.

3. Final Answer:

   type User { id: ID! name: String } -> Option D

4. Quick Check:

   Correct type syntax = type User { id: ID! name: String } [OK]

Hint: GraphQL types start with 'type' keyword and use braces {} [OK]

Common Mistakes:

• Using 'schema' instead of 'type' keyword
• Using parentheses instead of braces
• Omitting the 'type' keyword

3. Given this GraphQL schema snippet:

type Query { user(id: ID!): User }

And this query:

{ user(id: "123") { id name } }

What is the expected shape of the response data?

medium

A. {"user": {"id": "123", "name": "Alice"}}

B. {"data": {"user": {"id": "123", "name": "Alice"}}}

C. {"data": {"user": null}}

D. {"error": "User not found"}

Solution

1. Step 1: Understand GraphQL response format

   GraphQL responses wrap results inside a data object with requested fields.

2. Step 2: Match query and schema to response

   The query requests user with id "123" and fields id and name. Assuming user exists, response includes these inside data.

3. Final Answer:

   {"data": {"user": {"id": "123", "name": "Alice"}}} -> Option B

4. Quick Check:

   GraphQL response wraps data in 'data' key [OK]

Hint: GraphQL responses always wrap results inside 'data' key [OK]

Common Mistakes:

• Returning data without 'data' wrapper
• Confusing null user with error response
• Assuming error is returned instead of null

4. You wrote this schema test to check if the email field exists on User type:

expect(schema.getType('User').getFields()).toHaveProperty('email')

But the test fails. What is the most likely cause?

medium

A. The User type does not have an email field defined

B. The getFields() method is not valid on schema types

C. The test syntax is incorrect and should use hasProperty

D. The schema variable is undefined

Solution

1. Step 1: Understand what getFields() returns

   The getFields() method returns an object of fields defined on the type.

2. Step 2: Analyze test failure reason

   If test fails checking for 'email', likely the User type lacks that field in schema definition.

3. Final Answer:

   The User type does not have an email field defined -> Option A

4. Quick Check:

   Missing field causes test failure [OK]

Hint: Test fails if field is missing in schema type [OK]

Common Mistakes:

• Assuming method getFields() is invalid
• Confusing test assertion method names
• Not checking if schema variable is defined

5. You want to write a schema test to ensure the Post type has a field comments that returns a list of Comment types. Which test code correctly verifies this?

hard

A. expect(schema.getType('Post').getFields().comments.type.toString()).toBe('[Comment!]!')

B. expect(schema.getType('Post').getFields().comments.type.ofType.name).toBe('Comment')

C. expect(schema.getType('Post').getFields().comments.type.toString()).toBe('[Comment]')

D. expect(schema.getType('Post').getFields().comments.type.name).toBe('Comment')

Solution

1. Step 1: Understand GraphQL list and non-null syntax

   A list of Comment types with non-null items and non-null list is represented as [Comment!]!.

2. Step 2: Match test code to expected type string

   expect(schema.getType('Post').getFields().comments.type.toString()).toBe('[Comment!]!') checks the full type string including non-null markers, correctly verifying the list of non-null Comments.

3. Final Answer:

   expect(schema.getType('Post').getFields().comments.type.toString()).toBe('[Comment!]!') -> Option A

4. Quick Check:

   List of non-null Comments = '[Comment!]!' [OK]

Hint: Use toString() to check full list and non-null type syntax [OK]

Common Mistakes:

• Checking only inner type name without list brackets
• Ignoring non-null markers in type string
• Using wrong property to access type name