version: 1
id: go-testing-basics
title: Prove Behavior with Go Tests
summary: Extract a pure function and add a failing-then-passing unit test for payment fee calculation.
difficulty: intermediate
estimatedMinutes: 30
prerequisites: [http-json-api]
image: golang:1.22-alpine
shell: /bin/sh
setup:
  - "mkdir -p /workspace"
  - "cd /workspace && go mod init platformforge.local/fees >/dev/null"
tasks:
  - id: fee-tests
    title: Test FeeCents
    description: 'Create /workspace/fee.go with function FeeCents(amount int) int that returns 2% of amount in cents (integer math: amount*2/100). Create /workspace/fee_test.go with a test that expects FeeCents(1000) == 20. Run go test ./... successfully and write the output to /workspace/test-output.txt.'
    hints:
      - 'Package name can be fees or main; keep files in the same package.'
      - 'func TestFeeCents(t *testing.T) in fee_test.go'
      - go test ./... | tee /workspace/test-output.txt
    checks:
      - type: file
        name: Fee function defined
        path: /workspace/fee.go
        value: FeeCents
      - type: file
        name: Test file present
        path: /workspace/fee_test.go
        value: TestFeeCents
      - type: file
        name: Expects 20
        path: /workspace/fee_test.go
        value: "20"
      - type: command
        name: Tests pass
        command: "cd /workspace && go test ./..."
      - type: file
        name: Output captured
        path: /workspace/test-output.txt
        value: PASS
limits: {cpus: "1.0", memory: 512m, pids: 128, timeout: 1800, network: false}