Added basic file writing

file.go

@@ -0,0 +1,31 @@
+package nginxconf
+
+import "os"
+
+// File represents a nginx config file.
+// It wraps os.File
+type File struct {
+	*os.File
+}
+
+// OpenFile opens a nginx config file for writing only.
+// If the file does not exist at that path, it is created
+// with the permissions 0666.
+func OpenFile(path string) (*File, error) {
+	f, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE, 0666)
+	if err != nil {
+		return nil, err
+	}
+	return &File{f}, nil
+}
+
+// WriteDirective writes one directive to the file.
+// Call this function for each directive to write.
+func (f *File) WriteDirective(d *Directive) error {
+	b := []byte(d.String() + "\n")
+	_, err := f.Write(b)
+	if err != nil {
+		return err
+	}
+	return nil
+}

file_test.go

@@ -0,0 +1,50 @@
+package nginxconf
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func TestOpenFile(t *testing.T) {
+	f, err := OpenFile("example.conf")
+	if err != nil {
+		panic(err)
+	}
+
+	listen := NewDirective("listen", "80")
+	err = f.WriteDirective(listen)
+	if err != nil {
+		panic(err)
+	}
+
+	sname := NewDirective("server_name", "example.com", "www.example.com")
+	err = f.WriteDirective(sname)
+	if err != nil {
+		panic(err)
+	}
+
+	f.Close()
+
+	rf, err := os.OpenFile("example.conf", os.O_RDONLY, 0666)
+	if err != nil {
+		panic(err)
+	}
+
+	b, err := ioutil.ReadAll(rf)
+	if err != nil {
+		panic(err)
+	}
+
+	expected := fmt.Sprintf("%s\n%s\n", listen, sname)
+
+	if string(b) != expected {
+		t.Fail()
+	}
+
+	err = os.Remove("example.conf")
+	if err != nil {
+		panic(err)
+	}
+}