🌅 complete OS X keychain implementation.

Signed-off-by: David Calavera <david.calavera@gmail.com>

osxkeychain/osxkeychain_darwin_test.go

@@ -0,0 +1,37 @@
+package osxkeychain
+
+import (
+	"testing"
+
+	"github.com/calavera/docker-credential-helpers/credentials"
+)
+
+func TestOSXKeychainHelper(t *testing.T) {
+	creds := &credentials.Credentials{
+		ServerURL: "https://foobar.docker.io:2376/v1",
+		Username:  "foobar",
+		Password:  "foobarbaz",
+	}
+
+	helper := New()
+	if err := helper.Add(creds); err != nil {
+		t.Fatal(err)
+	}
+
+	username, password, err := helper.Get(creds.ServerURL)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if username != "foobar" {
+		t.Fatalf("expected %s, got %s\n", "foobar", username)
+	}
+
+	if password != "foobarbaz" {
+		t.Fatalf("expected %s, got %s\n", "foobarbaz", password)
+	}
+
+	if err := helper.Delete(creds.ServerURL); err != nil {
+		t.Fatal(err)
+	}
+}