first commit

README.md

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+# Week_12 - Operator dan Validasi (Golang)
+
+Project sederhana berisi dua paket:
+
+- `operator` : kalkulator aritmatika sederhana (Add, Sub, Mul, Div).
+- `validasi` : validasi usia produktif (18-60 tahun).
+
+Cara menjalankan test:
+
+```powershell
+cd "D:\Semester 3\Pratikum Back End\Week_12"
+go test ./...
+```
+
+Contoh menjalankan program demo:
+
+```powershell
+go run .
+```

go.mod

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+module example.com/week12
+
+go 1.20

main.go

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+package main
+
+import (
+	"fmt"
+
+	"example.com/week12/operator"
+	"example.com/week12/validasi"
+)
+
+func main() {
+    fmt.Println("Contoh penggunaan paket operator:")
+    a, b := 10, 3
+    fmt.Printf("%d + %d = %d\n", a, b, operator.Add(a,b))
+    fmt.Printf("%d - %d = %d\n", a, b, operator.Sub(a,b))
+    fmt.Printf("%d * %d = %d\n", a, b, operator.Mul(a,b))
+    if v, err := operator.Div(a,b); err == nil {
+        fmt.Printf("%d / %d = %v\n", a, b, v)
+    }
+
+    fmt.Println("\nContoh penggunaan paket validasi:")
+    ages := []int{17, 18, 30, 61}
+    for _, age := range ages {
+        fmt.Printf("Usia %d: produktif=%v\n", age, validasi.IsUsiaProduktif(age))
+    }
+}

operator/operator.go

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+package operator
+
+import "fmt"
+
+// Add returns the sum of a and b.
+func Add(a, b int) int {
+    return a + b
+}
+
+// Sub returns the difference a - b.
+func Sub(a, b int) int {
+    return a - b
+}
+
+// Mul returns the product of a and b.
+func Mul(a, b int) int {
+    return a * b
+}
+
+// Div returns the division a / b as float64. Returns an error on division by zero.
+func Div(a, b int) (float64, error) {
+    if b == 0 {
+        return 0, fmt.Errorf("divide by zero")
+    }
+    return float64(a) / float64(b), nil
+}

operator/operator_test.go

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+package operator
+
+import "testing"
+
+func TestAdd(t *testing.T) {
+    got := Add(2, 3)
+    if got != 5 {
+        t.Fatalf("Add(2,3) = %d; want 5", got)
+    }
+}
+
+func TestSub(t *testing.T) {
+    got := Sub(5, 3)
+    if got != 2 {
+        t.Fatalf("Sub(5,3) = %d; want 2", got)
+    }
+}
+
+func TestMul(t *testing.T) {
+    got := Mul(4, 3)
+    if got != 12 {
+        t.Fatalf("Mul(4,3) = %d; want 12", got)
+    }
+}
+
+func TestDiv(t *testing.T) {
+    got, err := Div(7, 2)
+    if err != nil {
+        t.Fatalf("unexpected error: %v", err)
+    }
+    if got != 3.5 {
+        t.Fatalf("Div(7,2) = %v; want 3.5", got)
+    }
+}
+
+func TestDivByZero(t *testing.T) {
+    _, err := Div(1, 0)
+    if err == nil {
+        t.Fatalf("expected error when dividing by zero")
+    }
+}

validasi/validasi.go

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+package validasi
+
+import "fmt"
+
+// IsUsiaProduktif returns true if age is between 18 and 60 inclusive.
+func IsUsiaProduktif(age int) bool {
+    return age >= 18 && age <= 60
+}
+
+// ValidateUsia returns nil when usia produktif, otherwise an error explaining why.
+func ValidateUsia(age int) error {
+    if age < 0 {
+        return fmt.Errorf("umur tidak boleh negatif")
+    }
+    if IsUsiaProduktif(age) {
+        return nil
+    }
+    return fmt.Errorf("umur %d bukan usia produktif (18-60)", age)
+}

validasi/validasi_test.go

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+package validasi
+
+import "testing"
+
+func TestIsUsiaProduktif(t *testing.T) {
+    cases := []struct{
+        age int
+        want bool
+    }{
+        {17, false},
+        {18, true},
+        {30, true},
+        {60, true},
+        {61, false},
+    }
+
+    for _, c := range cases {
+        got := IsUsiaProduktif(c.age)
+        if got != c.want {
+            t.Fatalf("IsUsiaProduktif(%d) = %v; want %v", c.age, got, c.want)
+        }
+    }
+}
+
+func TestValidateUsia(t *testing.T) {
+    if err := ValidateUsia(-1); err == nil {
+        t.Fatalf("expected error for negative age")
+    }
+    if err := ValidateUsia(18); err != nil {
+        t.Fatalf("unexpected error for age 18: %v", err)
+    }
+    if err := ValidateUsia(60); err != nil {
+        t.Fatalf("unexpected error for age 60: %v", err)
+    }
+    if err := ValidateUsia(61); err == nil {
+        t.Fatalf("expected error for age 61")
+    }
+}