di

di/greet.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+)
+
+func Greet(writer io.Writer, name string) {
+  fmt.Fprintf(writer, "Hello, %s", name)
+}
+
+func MyGreeterHandler(w http.ResponseWriter, r *http.Request) {
+  Greet(w, "world")
+}
+
+func main() {
+  log.Fatal(http.ListenAndServe(":5001", http.HandlerFunc(MyGreeterHandler)))
+}

di/greet_test.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestGreet(t *testing.T) {
+  buffer := bytes.Buffer{}
+  Greet(&buffer, "Chris")
+
+  got := buffer.String()
+  want := "Hello, Chris"
+
+  if got != want {
+    t.Errorf("got %q want %q", got, want)
+  }
+}