From 592ca0bc22d6000ffc7316bfb06fa107cccc695a Mon Sep 17 00:00:00 2001
From: Drew Bednar <drew@runcible.io>
Date: Wed, 19 Jun 2024 17:14:56 -0400
Subject: [PATCH] Dep injection

---
 .../dependency_injection/README.md            |  4 +++
 .../dependency_injection/go.mod               |  3 +++
 .../dependency_injection/greet.go             | 27 +++++++++++++++++++
 .../dependency_injection/greet_test.go        | 19 +++++++++++++
 4 files changed, 53 insertions(+)
 create mode 100644 learn_go_with_tests/dependency_injection/README.md
 create mode 100644 learn_go_with_tests/dependency_injection/go.mod
 create mode 100644 learn_go_with_tests/dependency_injection/greet.go
 create mode 100644 learn_go_with_tests/dependency_injection/greet_test.go

diff --git a/learn_go_with_tests/dependency_injection/README.md b/learn_go_with_tests/dependency_injection/README.md
new file mode 100644
index 0000000..cc2c39a
--- /dev/null
+++ b/learn_go_with_tests/dependency_injection/README.md
@@ -0,0 +1,4 @@
+# Dependency Injection
+
+https://quii.gitbook.io/learn-go-with-tests/go-fundamentals/dependency-injection
+
diff --git a/learn_go_with_tests/dependency_injection/go.mod b/learn_go_with_tests/dependency_injection/go.mod
new file mode 100644
index 0000000..d9b4671
--- /dev/null
+++ b/learn_go_with_tests/dependency_injection/go.mod
@@ -0,0 +1,3 @@
+module dependency_injection
+
+go 1.21.0
diff --git a/learn_go_with_tests/dependency_injection/greet.go b/learn_go_with_tests/dependency_injection/greet.go
new file mode 100644
index 0000000..a10d9c6
--- /dev/null
+++ b/learn_go_with_tests/dependency_injection/greet.go
@@ -0,0 +1,27 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+)
+
+func Greet(writer io.Writer, name string) {
+	fmt.Fprintf(writer, "Hello, %s\n", name)
+}
+
+// func main() {
+// 	Greet(os.Stdout, "Drew")
+// }
+
+// Here you can see that since now our greeter function takes an object that
+// implements the io.Writer interface we can now pass an object like the http.ResponseWriter
+// to it.
+func MyGreeterHandler(w http.ResponseWriter, r *http.Request) {
+	Greet(w, "world")
+}
+
+func main() {
+	log.Fatal(http.ListenAndServe(":5001", http.HandlerFunc(MyGreeterHandler)))
+}
diff --git a/learn_go_with_tests/dependency_injection/greet_test.go b/learn_go_with_tests/dependency_injection/greet_test.go
new file mode 100644
index 0000000..3da0b77
--- /dev/null
+++ b/learn_go_with_tests/dependency_injection/greet_test.go
@@ -0,0 +1,19 @@
+package main
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestGreet(t *testing.T) {
+	// The Buffer type from the bytes package implements the Writer interface, because it has the method Write(p []byte) (n int, err error)
+	buffer := bytes.Buffer{}
+	Greet(&buffer, "Chris")
+
+	got := buffer.String()
+	want := "Hello, Chris"
+
+	if got != want {
+		t.Errorf("got %q want %q", got, want)
+	}
+}