FULL_STACK_DEVELOPER_2026_COMPLETE - Phase 05 PowerShell API Testing and Contracts
PowerShell API Testing and Contracts Exercise TaskFlow HTTP directly before any browser integration
HTTP is the contract between independent programs.
REQUEST HTTP Client TaskFlow API
PowerShell / browser / later Next.js NestJS + Fastify RESPONSE
method + target + headers + optional body
status + headers + optional body
Figure - HTTP request/response exchange. Phase 05 studies the protocol before Phase 06 introduces a browser cross-origin call.
FULL_STACK_DEVELOPER_2026_COMPLETE - Phase 05 PowerShell API Testing and Contracts
Test the API without a frontend A backend should be independently testable. If every API test requires clicking through the UI, frontend bugs and API bugs become tangled. PowerShell gives us a direct client so we can see the raw contract before Phase 06 adds Next.js.
Start the server From: taskflow\apps\api
pnpm run start:devGET the collection PowerShell
GET one resource PowerShell
POST a new Todo PowerShell
$body = @{ title = 'Connect Next.js later' } | ConvertTo-Json
Invoke-RestMethod ` -Method Post ` -Uri 'http://127.0.0.1:4000/todos' ` -ContentType 'application/json' ` -Body $body
PowerShell line continuation uses the backtick. Avoid trailing spaces after the backtick because they can break continuation. You can also place the command on one line when troubleshooting.
PATCH an existing Todo PowerShell
$body = @{ completed = $true } | ConvertTo-Json
Invoke-RestMethod ` -Method Patch ` -Uri 'http://127.0.0.1:4000/todos/1' ` -ContentType 'application/json' ` -Body $body
DELETE and inspect status PowerShell - Invoke-WebRequest is useful when you want response metadata
FULL_STACK_DEVELOPER_2026_COMPLETE - Phase 05 PowerShell API Testing and Contracts
$response = Invoke-WebRequest ` -Method Delete ` -Uri 'http://127.0.0.1:4000/todos/2'
$response.StatusCode
Invoke-RestMethod conveniently deserializes JSON. Invoke-WebRequest exposes more response metadata directly. Choose based on what you are trying to observe.
Build a contract table while testing Request Expected success Expected content
GET /todos 200 OK Array of Todo representationsPOST /todos 201 Created Created Todo representationPATCH /todos/1 200 OK Updated Todo representationGET /todos/999 404 Not Found Structured Nest error representationWrite down the expected method, path, status and response shape before you send the request. Then compare expectation to observation. This is much more educational than repeatedly clicking Send until something looks right.
Official source notes Primary protocol reference: RFC 9110 - HTTP Semantics (RFC Editor). Supplemental developer reference: MDN HTTP Reference and HTTP Request Methods. Nest-specific routing and status behavior reference: NestJS Controllers documentation.
This phase teaches HTTP semantics independent of a specific transport version. HTTP/2 and HTTP/3 change framing and transport details, while request methods, target resources, headers, status codes and representation semantics remain the important application-level concepts for this course.
Tests are executable behavioral contracts. Good tests protect meaningful invariants and failure cases, not implementation trivia.
Restate the goal of “PowerShell API Testing and Contracts” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: behavior contract → arrange → act → assert → regression signal. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: A written TaskFlow API contract for tasks with request/response examples and deliberate error semantics.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
it("rejects deleting another member's task", async () => {
const response = await asUser(bob).delete(`/tasks/${aliceTask.id}`);
expect(response.status).toBe(403);
expect(await taskStillExists(aliceTask.id)).toBe(true);
});Do not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Look for shared database state, timers, globals, unordered execution, or missing cleanup before adding retries.
Move the highest-risk boundary to an integration test with the real adapter/database.
Without copying the final source, create a second small scenario that applies “PowerShell API Testing and Contracts” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Write an error envelope that the frontend can parse consistently.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Encoding actions into routes when resource semantics are clearer
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.