diff --git a/README.md b/README.md
index e838807..28f4c9f 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ func main() {
 	req := appstore.IAPRequest{
 		ReceiptData: "your receipt data encoded by base64",
 	}
-	resp, err := client.Verify(&req)
+	resp, err := client.Verify(req)
 }
 ```
 
diff --git a/appstore/validator_test.go b/appstore/validator_test.go
index a2e5fde..9e32f12 100644
--- a/appstore/validator_test.go
+++ b/appstore/validator_test.go
@@ -2,6 +2,10 @@ package appstore
 
 import (
 	"errors"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
 	"reflect"
 	"testing"
 	"time"
@@ -79,6 +83,21 @@ func TestNew(t *testing.T) {
 	}
 }
 
+func TestNewWithEnvironment(t *testing.T) {
+	expected := Client{
+		URL:     "https://buy.itunes.apple.com/verifyReceipt",
+		TimeOut: time.Second * 5,
+	}
+
+	os.Setenv("IAP_ENVIRONMENT", "production")
+	actual := New()
+	os.Clearenv()
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
 func TestNewWithConfig(t *testing.T) {
 	config := Config{
 		IsProduction: true,
@@ -96,6 +115,22 @@ func TestNewWithConfig(t *testing.T) {
 	}
 }
 
+func TestNewWithConfigTimeout(t *testing.T) {
+	config := Config{
+		IsProduction: true,
+	}
+
+	expected := Client{
+		URL:     "https://buy.itunes.apple.com/verifyReceipt",
+		TimeOut: time.Second * 5,
+	}
+
+	actual := NewWithConfig(config)
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
 func TestVerify(t *testing.T) {
 	client := New()
 
@@ -110,3 +145,46 @@ func TestVerify(t *testing.T) {
 		t.Errorf("got %v\nwant %v", actual, expected)
 	}
 }
+
+func TestVerifyErrors(t *testing.T) {
+	server, client := testTools(199, "dummy response")
+	defer server.Close()
+
+	req := IAPRequest{
+		ReceiptData: "dummy data",
+	}
+
+	expected := errors.New("An error occurred in IAP - code:199")
+	_, actual := client.Verify(req)
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
+func TestVerifyTimeout(t *testing.T) {
+	// HTTP 100 is "continue" so it will time out
+	server, client := testTools(100, "dummy response")
+	defer server.Close()
+
+	req := IAPRequest{
+		ReceiptData: "dummy data",
+	}
+
+	expected := errors.New("")
+	_, actual := client.Verify(req)
+	if !reflect.DeepEqual(reflect.TypeOf(actual), reflect.TypeOf(expected)) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
+func testTools(code int, body string) (*httptest.Server, *Client) {
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(code)
+		w.Header().Set("Content-Type", "application/json")
+		fmt.Fprintln(w, body)
+	}))
+
+	client := &Client{URL: server.URL, TimeOut: time.Second * 2}
+	return server, client
+}
diff --git a/playstore/validator_test.go b/playstore/validator_test.go
index ce2525e..248944e 100644
--- a/playstore/validator_test.go
+++ b/playstore/validator_test.go
@@ -1,6 +1,7 @@
 package playstore
 
 import (
+	"errors"
 	"os"
 	"reflect"
 	"testing"
@@ -27,6 +28,18 @@ func TestInit(t *testing.T) {
 	}
 }
 
+func TestInitWithoutClientSecret(t *testing.T) {
+	expected := errors.New("Client Secret Key is required")
+
+	os.Setenv("IAB_CLIENT_ID", "dummyId")
+	actual := Init()
+	os.Clearenv()
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
 func TestInitWithConfig(t *testing.T) {
 	expected := &oauth.Config{
 		ClientId:     "dummyId",
@@ -50,6 +63,34 @@ func TestInitWithConfig(t *testing.T) {
 	}
 }
 
+func TestInitWithConfigErrors(t *testing.T) {
+	expected := errors.New("Client ID is required")
+
+	config := &oauth.Config{
+		Scope:    "https://www.googleapis.com/auth/androidpublisher",
+		AuthURL:  "https://accounts.google.com/o/oauth2/auth",
+		TokenURL: "https://accounts.google.com/o/oauth2/token",
+	}
+	actual := InitWithConfig(config)
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+
+	expected = errors.New("Client Secret Key is required")
+	config = &oauth.Config{
+		ClientId: "dummyId",
+		Scope:    "https://www.googleapis.com/auth/androidpublisher",
+		AuthURL:  "https://accounts.google.com/o/oauth2/auth",
+		TokenURL: "https://accounts.google.com/o/oauth2/token",
+	}
+	actual = InitWithConfig(config)
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
 func TestNew(t *testing.T) {
 	// Initialize config
 	_config := &oauth.Config{
@@ -106,6 +147,16 @@ func TestVerifySubscription(t *testing.T) {
 	// TODO Nomal scenario
 }
 
+func TestVerifySubscriptionAndroidPublisherError(t *testing.T) {
+	client := Client{nil}
+	expected := errors.New("client is nil")
+	_, actual := client.VerifySubscription("package", "subscriptionID", "purchaseToken")
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}
+
 func TestVerifyProduct(t *testing.T) {
 	Init()
 
@@ -126,3 +177,13 @@ func TestVerifyProduct(t *testing.T) {
 
 	// TODO Nomal scenario
 }
+
+func TestVerifyProductAndroidPublisherError(t *testing.T) {
+	client := Client{nil}
+	expected := errors.New("client is nil")
+	_, actual := client.VerifyProduct("package", "productID", "purchaseToken")
+
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("got %v\nwant %v", actual, expected)
+	}
+}