Add package arrays

arrays/sum.go

@@ -0,0 +1,9 @@
+package main
+
+func Sum(numbers []int) int {
+	sum := 0
+	for _, n := range numbers {
+		sum += n
+	}
+	return sum
+}

arrays/sum_test.go

@@ -0,0 +1,29 @@
+package main
+
+import "testing"
+
+func TestSum(t *testing.T) {
+
+	t.Run("collection of 5 numbers", func(t *testing.T) {
+		numbers := []int{1, 2, 3, 4, 5}
+
+		got := Sum(numbers)
+		want := 15
+
+		if got != want {
+			t.Errorf("got %d want %d given, %v", got, want, numbers)
+		}
+	})
+
+	t.Run("collection of any size", func(t *testing.T) {
+		numbers := []int{1, 2, 3}
+
+		got := Sum(numbers)
+		want := 6
+
+		if got != want {
+			t.Errorf("got %d want %d given, %v", got, want, numbers)
+		}
+	})
+
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/halfdan/learn-go-with-tests
+
+go 1.17

hello/hello.go

@@ -0,0 +1,33 @@
+package main
+
+import "fmt"
+
+const spanish = "Spanish"
+const french = "French"
+
+const englishHelloPrefix = "Hello, "
+const spanishHelloPrefix = "Hola, "
+const frenchHelloPrefix = "Bonjour, "
+
+func Hello(name string, language string) string {
+	if name == "" {
+		name = "World"
+	}
+
+	return greetingPrefix(language) + name
+}
+
+func greetingPrefix(language string) (prefix string) {
+	switch language {
+	case french:
+		prefix = frenchHelloPrefix
+	case spanish:
+		prefix = spanishHelloPrefix
+	default:
+		prefix = englishHelloPrefix
+	}
+	return
+}
+func main() {
+	fmt.Println(Hello("world", ""))
+}

hello/hello_test.go

@@ -0,0 +1,28 @@
+package main
+
+import "testing"
+
+func TestHello(t *testing.T) {
+	assertCorrectMessage := func(t testing.TB, got, want string) {
+		t.Helper()
+		if got != want {
+			t.Errorf("got %q want %q", got, want)
+		}
+	}
+
+	t.Run("saying hello to people", func(t *testing.T) {
+		got := Hello("Chris", "")
+		want := "Hello, Chris"
+		assertCorrectMessage(t, got, want)
+	})
+	t.Run("empty string defaults to 'World'", func(t *testing.T) {
+		got := Hello("", "")
+		want := "Hello, World"
+		assertCorrectMessage(t, got, want)
+	})
+	t.Run("in Spanish", func(t *testing.T) {
+		got := Hello("Elodie", "Spanish")
+		want := "Hola, Elodie"
+		assertCorrectMessage(t, got, want)
+	})
+}

integers/adder.go

@@ -0,0 +1,6 @@
+package integers
+
+// Add takes two integers and return the sum of them.
+func Add(a, b int) int {
+	return a + b
+}

integers/adder_test.go

@@ -0,0 +1,21 @@
+package integers
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestAdder(t *testing.T) {
+	sum := Add(2, 2)
+	expected := 4
+
+	if sum != expected {
+		t.Errorf("expected %v, got %v", expected, sum)
+	}
+}
+
+func ExampleAdd() {
+	sum := Add(1, 5)
+	fmt.Println(sum)
+	// Output: 6
+}

iteration/repeat.go

@@ -0,0 +1,16 @@
+package iteration
+
+import "strings"
+
+func Repeat(character string, count int) string {
+	var repeated string
+
+	for i := 0; i < count; i++ {
+		repeated += character
+	}
+	return repeated
+}
+
+func StringsRepeat(s string, count int) string {
+	return strings.Repeat(s, count)
+}

iteration/repeat_test.go

@@ -0,0 +1,32 @@
+package iteration
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestRepeat(t *testing.T) {
+	repeated := Repeat("a", 5)
+	expected := "aaaaa"
+
+	if repeated != expected {
+		t.Errorf("expected %v, got %v", expected, repeated)
+	}
+}
+
+func BenchmarkRepeat(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Repeat("a", 5)
+	}
+}
+func BenchmarkStringsRepeat(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		StringsRepeat("a", 5)
+	}
+}
+
+func ExampleRepeat() {
+	data := Repeat("a", 5)
+	fmt.Println(data)
+	// Outputs: aaaaa
+}