Creating and Configuring Mocks

Overview

This guide walks you through the API Mocks screens exactly as they appear in Shift Left Studio, from opening the module to serving a mock over HTTP. A mock is a saved fake response (a path + method + one or more configured responses) that the mock server returns so you can build and test against APIs that don't exist yet or aren't available.

Conceptual background: Understanding mocks. Explore the capability at mock server.

Before you begin

• You need a project with at least one endpoint if you want to link mocks to endpoints or bulk-generate them. If you have none yet, see Import and discover endpoints.
• Mock creation is license-gated, and the number of mocks is capped on the Free edition (50). Professional and Enterprise are unlimited.
• No AI key is required — generation is built from your API schema, not an AI model.

Step 1 — Open API Mocks and select a project

1. In the top navigation bar, click Mocks. (The Mocks item is highlighted while you're in the module.)
2. The API Mocks page opens with a one-line description explaining that mocks can replace real API calls during test execution or run as a standalone server.
3. Scroll to Select a project and click a project card (for example Pet Store). The mocks table for that project opens.
4. To switch projects later, use the All projects control at the top of the mocks view to return to the project picker.

Step 2 — Choose how to create mocks

In the header above the mocks table you'll see these buttons:

• Start Mock Server — starts serving your active mocks (covered in Step 6).
• Create Mock (blue) — build one mock by hand.
• Generate Mock (purple, sparkle icon) — bulk-create mocks from your endpoints' schemas.

Use Generate Mock to seed many mocks quickly, then refine them; use Create Mock for one-off or standalone mocks.

Step 3 — Bulk-generate mocks from endpoints

1. Click Generate Mock. A dialog titled Generate Mocks opens and loads your features and endpoints as a checkbox tree.
2. Narrow the list with the Search features and endpoints… box, or use Select All / Deselect All. Expand a feature to toggle individual endpoints; the feature checkbox toggles all of its endpoints at once.
3. Watch the counter — it reads N of M endpoints selected. You must select at least one, or you'll see "Please select at least one endpoint to generate mocks for."
4. Click the footer Generate Mocks button. For each endpoint, the response body is built deterministically from the endpoint's OpenAPI/JSON schema (WSDL example XML for SOAP, a data envelope for GraphQL) — no AI model is called.
5. If a selected endpoint already has a mock, a Resolve Mock Conflicts dialog appears. For each endpoint choose one of:
   • Skip (keep existing) — leave the current mock untouched (this is the default).
   • Update existing — overwrite the current mock with the freshly generated one.
   • Create duplicate — add a second mock (named with a (Copy) suffix). Use Skip All / Update All / Duplicate All to apply one choice to every conflict, then click Continue.
6. A progress indicator shows Generating X of Y…. When it finishes you'll see a summary such as "Successfully generated mocks: 6 created, 2 updated, 1 skipped." The new mocks appear in the table.

Step 4 — Create a mock manually

1. Click Create Mock. The response editor opens.
2. Enter a Name (required) and an optional Description.
3. Link to Endpoint (Optional) — choose an endpoint from the dropdown to auto-fill and lock its Path and Method (SOAP endpoints also expose SOAP Operation and SOAP Action), or choose None – Create Standalone Mock and set them yourself:
   • Path — must start with a leading slash, e.g. /api/users/:id. If it doesn't, you'll see "Path must start with a leading slash."
   • Method — GET, POST, PUT, DELETE, PATCH, HEAD, or OPTIONS.
4. Response Type — choose Static (Fixed JSON) for a fixed body, or Dynamic (Template with Variables) for a body built at request time.
5. Configure one or more responses (see Step 5).
6. If you added more than one response, pick which one is returned when no conditions match using Default Response.
7. Click Create Mock (the button reads Update Mock when editing). The mock appears in the table.

Step 5 — Configure a response

Each mock holds one or more named responses. Click Add Response to add another; use the trash icon to remove one. For each response set:

Static body: Enter valid JSON in Body (JSON) (or XML for SOAP). Two helpers speed this up — Fill standard error inserts an { error, code } shape, and Fill standard success inserts a { message } shape.

Dynamic template: Switch Response Type to Dynamic, then enter a Template using {{ … }} variables that resolve per request:

• Random/utility: {{uuid}}, {{timestamp}}, {{date}}, {{randomInt}}, {{randomInt(100)}}, {{randomFloat}}
• Echo the request: {{request.query.param}}, {{request.headers.name}}, {{request.body.some.path}}, {{request.path.id}}

Example template: {"id": {{uuid}}, "name": "User {{randomInt}}", "requestedId": "{{request.query.id}}"}.

Step 6 — Start the mock server and call your mocks

1. Click Start Mock Server. Only active mocks are served.
2. The UI shows two base URLs — copy whichever fits your setup:
   • Path-based (local / same server) — no DNS needed; use it when the engine runs on your machine or the same server.
   • Subdomain (centralized) — use it when your company has DNS for a central engine (e.g. *.{projectId}.mock.<your-domain>). Ask your admin if unsure.
3. Open the How to Use panel for ready-to-copy cURL, JavaScript (Fetch), Python (requests), and Node.js (axios) snippets pointed at your mock.
4. Call the mock from your client — you should get the configured status, headers, and body back (after any Delay). If you get 404 "No active mock found", confirm the mock is Active and the path/method match; if you get 503 "Mock server not running", start the server.

Manage the mocks table

• Toolbar: Search mocks (filter by name/path), Grouping (e.g. by feature), Columns (show/hide), and a count such as Showing 8 of 8 mocks.
• Columns: Status (Active/Inactive), Mock name + description, Feature, Endpoint (method badge + path), Type (static/dynamic), Responses (count), Created.
• Row actions: Play (test the mock with a sample request and see the status/headers/body without hitting the running server), toggle Active/Inactive, Edit, Delete.
• Bulk actions: select rows to activate, deactivate, or delete several mocks at once.

Troubleshooting

• "Please select at least one endpoint…" — you clicked Generate Mocks with nothing selected; tick an endpoint first.
• Mock not returned (404) — the mock is inactive, or the request path/method doesn't match. Toggle it Active and verify the path.
• Invalid JSON error on save — the Body or Headers field isn't valid JSON. Fix the syntax (use the Fill standard… helpers as a starting point).
• Reached your mock limit — Free is capped at 50 mocks; deactivate/delete unused mocks or upgrade.

Related articles

• Understanding mocks
• Endpoint management
• Test execution
• Understanding workflows