initial commit

greetings/go.mod

@@ -0,0 +1,3 @@
+module example.com/greetings
+
+go 1.24.2

greetings/greetings.go

@@ -0,0 +1,37 @@
+package greetings
+
+import (
+	"errors"
+	"fmt"
+	"math/rand"
+)
+
+func Hello(name string) (string, error) {
+	if name == "" {
+		return name, errors.New("empty name")
+	}
+	message := fmt.Sprintf(randomFormat(), name)
+	return message, nil
+}
+
+func Hellos(names []string) (map[string]string, error) {
+	messages := make(map[string]string)
+	for _, name := range names {
+		message, err := Hello(name)
+		if err != nil {
+			return nil, err
+		}
+		messages[name] = message
+	}
+	return messages, nil
+}
+
+func randomFormat() string {
+	formats := []string{
+		"Hi, %v. Welcome!",
+		"Great to see you, %v!",
+		"Hail, %v! Well met!",
+	}
+
+	return formats[rand.Intn(len(formats))]
+}

greetings/greetings_test.go

@@ -0,0 +1,26 @@
+package greetings
+
+import (
+	"regexp"
+	"testing"
+)
+
+// TestHelloName calls greetings.Hello with a name, checking
+// for a valid return value.
+func TestHelloName(t *testing.T) {
+	name := "Gladys"
+	want := regexp.MustCompile(`\b` + name + `\b`)
+	msg, err := Hello("Gladys")
+	if !want.MatchString(msg) || err != nil {
+		t.Errorf(`Hello("Gladys") = %q, %v, want match for %#q, nil`, msg, err, want)
+	}
+}
+
+// TestHelloEmpty calls greetings.Hello with an empty string,
+// checking for an error.
+func TestHelloEmpty(t *testing.T) {
+	msg, err := Hello("")
+	if msg != "" || err == nil {
+		t.Errorf(`Hello("") = %q, %v, want "", error`, msg, err)
+	}
+}

hello/go.mod

@@ -0,0 +1,7 @@
+module example.com/hello
+
+go 1.24.2
+
+replace example.com/greetings => ../greetings
+
+require example.com/greetings v0.0.0-00010101000000-000000000000

hello/hello.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"example.com/greetings"
+)
+
+func main() {
+	log.SetPrefix("greetings: ")
+	log.SetFlags(0)
+
+	names := []string{"Gladys", "Samantha", "Darrin"}
+
+	messages, err := greetings.Hellos(names)
+	if err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println(messages)
+}