testing

Testing Standards — order-service

Coverage Target: 80%

TDD Style: Strict TDD — Tests MUST Come First

1. RED: Write a failing test that specifies the behavior
2. GREEN: Write minimum code to make it pass
3. REFACTOR: Clean up while tests stay green

NEVER write implementation before its test exists.

Test File Conventions

Convention	Value
Location	Co-located (*_test.go next to source file)
Naming	*_test.go
Runner	go test ./...
Coverage	go test ./... -coverprofile=cover.out

Test Structure

Use table-driven tests for multiple scenarios:

func TestCalculateTotal(t *testing.T) {
    tests := []struct {
        name     string
        items    []Item
        expected float64
    }{
        {"empty cart", nil, 0},
        {"single item", []Item{{Price: 10}}, 10},
        {"multiple items", []Item{{Price: 10}, {Price: 20}}, 30},
    }
    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            got := CalculateTotal(tt.items)
            assert.Equal(t, tt.expected, got)
        })
    }
}

Test Categories

1. Unit tests: Isolated, fast, mock external dependencies
2. Integration tests: Test component boundaries with testcontainers

Rules

• Each test tests ONE behavior
• Test names describe the scenario, not the implementation
• No shared mutable state between tests
• Mock external services (APIs, databases) in unit tests
• Integration tests use testcontainers for real dependencies