Files
crib/samples/go.go

96 lines
1.4 KiB
Go

// file: go.go
package example_test
import (
"context"
"fmt"
"math"
"sync"
"testing"
"time"
)
// Simple interface
type Adder interface {
Add(a, b int) int
}
// Concrete implementation
type Calculator struct{}
func (Calculator) Add(a, b int) int {
return a + b
}
// Generic helper
func Max[T ~int | ~float64](a, b T) T {
if a > b {
return a
}
return b
}
// Table-driven test
func TestAdd(t *testing.T) {
tests := []struct {
name string
a, b int
expected int
}{
{"positive", 2, 3, 5},
{"negative", -2, -3, -5},
{"mixed", -2, 5, 3},
}
var calc Adder = Calculator{}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := calc.Add(tt.a, tt.b); got != tt.expected {
t.Fatalf("Add(%d, %d) = %d; want %d",
tt.a, tt.b, got, tt.expected)
}
})
}
}
// Concurrency + context test
func TestWorker(t *testing.T) {
ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
defer cancel()
ch := make(chan int)
var wg sync.WaitGroup
wg.Add(1)
go func() {
defer wg.Done()
select {
case ch <- 42:
case <-ctx.Done():
}
}()
select {
case v := <-ch:
if v != 42 {
t.Errorf("unexpected value: %d", v)
}
case <-ctx.Done():
t.Fatal("timed out")
}
wg.Wait()
}
// Raw string + math edge case
func TestRawString(t *testing.T) {
raw := `line 1
line 2
\t not escaped
`
if len(raw) == 0 || math.IsNaN(float64(len(raw))) {
t.Fatal("impossible condition reached")
}
}