Snapshot testing queries in GraphQL - Step-by-Step Execution

Concept Flow - Snapshot testing queries

Write GraphQL Query

↓

Run Query Against API

↓

Capture Response Snapshot

↓

Compare New Response to Snapshot

↓

Test Pass

This flow shows how a GraphQL query is run, its response saved as a snapshot, and future runs compare responses to detect changes.

Execution Sample

GraphQL

query GetUser {
  user(id: "1") {
    id
    name
    email
  }
}

This GraphQL query fetches user details by ID to create or verify a snapshot of the response.

Execution Table

Step	Action	Query/Response	Snapshot State	Test Result
1	Write Query	query GetUser { user(id: "1") { id name email } }	No snapshot yet	N/A
2	Run Query	Sent to API	No snapshot yet	N/A
3	Capture Response	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }	Snapshot created	N/A
4	Run Query Again	Sent to API	Snapshot exists	N/A
5	Compare Response	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }	Matches snapshot	Pass
6	Run Query Again	Sent to API	Snapshot exists	N/A
7	Compare Response	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }	Differs from snapshot	Fail

💡 Test stops after detecting a mismatch or confirming match with snapshot.

Variable Tracker

Variable	Start	After Step 3	After Step 5	After Step 7
snapshot	null	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }	Same as step 3	Same as step 3
response	null	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }	{ user: { id: "1", name: "Alice", email: "[e-mail]" } }
testResult	N/A	N/A	Pass	Fail

Key Moments - 2 Insights

Why does the test fail even if only the email changed?

Because snapshot testing compares the entire response exactly, any difference like email change causes a mismatch (see execution_table row 7).

What happens if there is no existing snapshot?

The first run captures and saves the response as a snapshot (see execution_table row 3), so future tests have a baseline to compare.

Visual Quiz - 3 Questions

Look at the execution_table, what is the test result at step 5?

A No snapshot

B Fail

C Pass

D Test not run

💡 Hint

Check the 'Test Result' column at step 5 in the execution_table.

At which step does the snapshot get created?

A Step 3

B Step 2

C Step 4

D Step 5

💡 Hint

Look for 'Snapshot created' in the 'Snapshot State' column.

If the response changes, what happens to the test result?

A It passes

B It fails

C Snapshot updates automatically

D Test is skipped

💡 Hint

See step 7 in execution_table where response differs and test result is 'Fail'.

Concept Snapshot

Snapshot Testing Queries:
- Write a GraphQL query.
- Run query and capture response as snapshot.
- On future runs, compare response to snapshot.
- If identical, test passes.
- If different, test fails and needs review.

Full Transcript

Snapshot testing queries involves writing a GraphQL query and running it against an API. The first time, the response is saved as a snapshot. Later runs compare the new response to this snapshot. If they match exactly, the test passes. If there is any difference, such as a changed email, the test fails. This helps catch unexpected changes in API responses.