diff --git a/README.md b/README.md
index 3f99bfc..0bccd82 100644
--- a/README.md
+++ b/README.md
@@ -28,17 +28,17 @@ import "github.com/irlndts/go-discogs"
 Some requests require authentification (as any user). According to [Discogs](https://www.discogs.com/developers/#page:authentication,header:authentication-discogs-auth-flow), to send requests with Discogs Auth, you have two options: sending your credentials in the query string with key and secret parameters or a [token parameter](https://www.discogs.com/settings/developers).
 This is token way example:
 ```go
-client := discogs.NewClient().UserAgent("TestDiscogsClient/0.0.1 +example.com").Token("Some Token")
+client, err := discogs.NewClient(&discogs.Options{
+        UserAgent: "Some Name",
+        Currency:  "EUR", // optional, "USD" (default), "GBP", "EUR", "CAD", "AUD", "JPY", "CHF", "MXN", "BRL", "NZD", "SEK", "ZAR" are allowed
+        Token:     "Some Token", // optional
+        URL:       "https://api.discogs.com",
+    })
 ``` 
 
-Don't forget to set required currency ("USD", "GBP", "EUR", "CAD", "AUD", "JPY", "CHF", "MXN", "BRL", "NZD", "SEK", "ZAR" are allowed):
-```go
-err := client.Currency("EUR");
-```
-
 #### Releases
 ```go
-  release, err := client.Release(9893847)
+  release, err := client.Release.Release(9893847)
   fmt.Println(release.Artists[0].Name, " - ", release.Title) 
   // St. Petersburg Ska-Jazz Review  -  Elephant Riddim
 ```
diff --git a/artists_test.go b/artists_test.go
deleted file mode 100644
index 45000b0..0000000
--- a/artists_test.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package discogs
-
-import (
-	"fmt"
-	"testing"
-)
-
-func TestArtistService_Artist(t *testing.T) {
-	expectedId := 1000
-
-	d, _ := NewClient(&Options{})
-	artist, _, err := d.Artist.Artist(&ArtistParams{Artist_id: "1000"})
-
-	check(t, err)
-	assert(t, artist.Id == expectedId, fmt.Sprintf("Release.Title looked for %d, and received %d ", expectedId, artist.Id))
-}
-
-func TestArtistService_Releases(t *testing.T) {
-	expectedArtist := "Dave Clarke"
-
-	d, _ := NewClient(&Options{})
-	releases, _, err := d.Artist.Releases(&ArtistParams{Artist_id: "1000", Sort: "year", Sort_order: "desc"})
-
-	check(t, err)
-	assert(t, releases.Releases[0].Artist == expectedArtist, fmt.Sprintf("Releses.Artist looked for %s, and received %s ", expectedArtist, releases.Releases[0].Artist))
-}
diff --git a/discogs.go b/discogs.go
index 4c3e5bb..58f1fa9 100644
--- a/discogs.go
+++ b/discogs.go
@@ -1,8 +1,11 @@
 package discogs
 
 import (
+	"encoding/json"
 	"fmt"
+	"io/ioutil"
 	"net/http"
+	"net/url"
 
 	"github.com/irlndts/go-apirequest"
 )
@@ -27,15 +30,20 @@ type Client struct {
 	Search  *SearchService
 }
 
+var header *http.Header
+
 // NewClient returns a new Client.
 func NewClient(o *Options) (*Client, error) {
-	header := &http.Header{}
+	header = &http.Header{}
 	base := apirequest.New().Client(&http.Client{}).Base(discogsAPI)
-	if o.UserAgent != "" {
-		base.Set("User-Agent", o.UserAgent)
-		header.Add("User-Agent", o.UserAgent)
+
+	if o == nil || o.UserAgent == "" {
+		return nil, fmt.Errorf("failed to set user-agent")
 	}
 
+	base.Set("User-Agent", o.UserAgent)
+	header.Add("User-Agent", o.UserAgent)
+
 	cur, err := currency(o.Currency)
 	if err != nil {
 		return nil, err
@@ -47,8 +55,12 @@ func NewClient(o *Options) (*Client, error) {
 		header.Add("Authorization", "Discogs token="+o.Token)
 	}
 
+	if o.URL == "" {
+		o.URL = discogsAPI
+	}
+
 	return &Client{
-		Release: newReleaseService(o.URL+"/releases/", header, cur),
+		Release: newReleaseService(o.URL+"/releases/", cur),
 		Artist:  newArtistService(base.New()),
 		Label:   newLabelService(base.New()),
 		Master:  newMasterService(base.New()),
@@ -69,3 +81,24 @@ func currency(c string) (string, error) {
 		return "", fmt.Errorf("%v\n", "Invalid currency abbreviation.")
 	}
 }
+
+func request(path string, params url.Values, resp interface{}) error {
+	r, err := http.NewRequest("GET", path+"?"+params.Encode(), nil)
+	if err != nil {
+		return err
+	}
+	r.Header = *header
+
+	client := &http.Client{}
+	response, err := client.Do(r)
+	if err != nil {
+		return err
+	}
+
+	body, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return err
+	}
+
+	return json.Unmarshal(body, &resp)
+}
diff --git a/discogs_test.go b/discogs_test.go
index b58defb..b08d0d0 100644
--- a/discogs_test.go
+++ b/discogs_test.go
@@ -20,3 +20,23 @@ func assert(t *testing.T, condition bool, assertion string) {
 		t.Errorf("Assertion failed: %v", assertion)
 	}
 }
+
+func initDiscogsClient(t *testing.T, options *Options) *Client {
+	if options == nil {
+		options = &Options{
+			UserAgent: testUserAgent,
+			Currency:  "USD",
+		}
+	}
+
+	if options.UserAgent == "" {
+		options.UserAgent = testUserAgent
+	}
+
+	client, err := NewClient(options)
+	if err != nil {
+		t.Fatalf("failed to create client: %s", err)
+	}
+
+	return client
+}
diff --git a/labels_test.go b/labels_test.go
deleted file mode 100644
index 8084584..0000000
--- a/labels_test.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package discogs
-
-import (
-	"fmt"
-	"testing"
-)
-
-func TestLabelService_Label(t *testing.T) {
-	expectedId := 1000
-
-	d, _ := NewClient(&Options{})
-	label, _, err := d.Label.Label(&LabelParams{Label_id: "1000"})
-
-	check(t, err)
-	assert(t, label.Id == expectedId, fmt.Sprintf("Release.Title looked for %d, and received %d ", expectedId, label.Id))
-}
-
-func TestLabelService_Releases(t *testing.T) {
-	expectedId := "Ghetto Sol"
-
-	d, _ := NewClient(&Options{})
-	label, _, err := d.Label.Releases(&LabelParams{Label_id: "1000"})
-
-	check(t, err)
-	assert(t, label.Releases[0].Title == expectedId, fmt.Sprintf("Release.Title looked for %s, and received %s ", expectedId, label.Releases[0].Title))
-}
diff --git a/masters_test.go b/masters_test.go
deleted file mode 100644
index 37a1c68..0000000
--- a/masters_test.go
+++ /dev/null
@@ -1,26 +0,0 @@
-package discogs
-
-import (
-	"fmt"
-	"testing"
-)
-
-func TestMasterService_Master(t *testing.T) {
-	expectedTitle := "Elephant Riddim"
-
-	d, _ := NewClient(nil)
-	master, _, err := d.Master.Master(&MasterParams{Master_id: "960657"})
-
-	check(t, err)
-	assert(t, master.Title == expectedTitle, fmt.Sprintf("master.Title looked for %s, and received %s ", expectedTitle, master.Title))
-}
-
-func TestMasterService_Versions(t *testing.T) {
-	expectedTitle := "Stardiver"
-
-	d, _ := NewClient(nil)
-	versions, _, err := d.Master.Versions(&MasterVersionParams{Master_id: "1000", Page: 1, Per_page: 1})
-
-	check(t, err)
-	assert(t, versions.Versions[0].Title == expectedTitle, fmt.Sprintf("master.Title looked for %s, and received %s ", expectedTitle, versions.Versions[0].Title))
-}
diff --git a/releases.go b/releases.go
index 9949701..70ac30b 100644
--- a/releases.go
+++ b/releases.go
@@ -1,9 +1,6 @@
 package discogs
 
 import (
-	"encoding/json"
-	"io/ioutil"
-	"net/http"
 	"net/url"
 	"strconv"
 )
@@ -52,14 +49,12 @@ type ReqRelease struct {
 // ReleaseService ...
 type ReleaseService struct {
 	url      string
-	header   *http.Header
 	currency string
 }
 
-func newReleaseService(url string, header *http.Header, currency string) *ReleaseService {
+func newReleaseService(url string, currency string) *ReleaseService {
 	return &ReleaseService{
 		url:      url,
-		header:   header,
 		currency: currency,
 	}
 }
@@ -70,34 +65,9 @@ func (s *ReleaseService) Release(releaseID int) (*Release, error) {
 	params.Set("CurrAbbr", s.currency)
 
 	var release *Release
-	if err := s.request(strconv.Itoa(releaseID), params, &release); err != nil {
+	if err := request(s.url+strconv.Itoa(releaseID), params, &release); err != nil {
 		return nil, err
 	}
 
 	return release, nil
 }
-
-func (s *ReleaseService) request(path string, params url.Values, resp interface{}) error {
-	r, err := http.NewRequest("GET", s.url+path+"?"+params.Encode(), nil)
-	if err != nil {
-		return err
-	}
-	r.Header = *s.header
-
-	client := &http.Client{}
-	response, err := client.Do(r)
-	if err != nil {
-		return err
-	}
-
-	body, err := ioutil.ReadAll(response.Body)
-	if err != nil {
-		return err
-	}
-
-	if err = json.Unmarshal(body, &resp); err != nil {
-		return err
-	}
-
-	return nil
-}
diff --git a/releases_test.go b/releases_test.go
index c9313b6..75fb4e9 100644
--- a/releases_test.go
+++ b/releases_test.go
@@ -1,7 +1,6 @@
 package discogs
 
 import (
-	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -19,12 +18,13 @@ func TestReleaseServiceRelease(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(ReleaseServer))
 	defer ts.Close()
 
-	d, err := NewClient(&Options{URL: ts.URL})
-	if err != nil {
-		t.Fatalf("failed to create client: %s", err)
-	}
+	d := initDiscogsClient(t, &Options{URL: ts.URL})
 	release, err := d.Release.Release(8138518)
+	if err != nil {
+		t.Fatalf("failed to get release: %s", err)
+	}
 
-	check(t, err)
-	assert(t, release.Title == expectedTitle, fmt.Sprintf("Release.Title looked for %s, and received %s ", expectedTitle, release.Title))
+	if release.Title != expectedTitle {
+		t.Fatalf("release title got=%s want=%s ", expectedTitle, release.Title)
+	}
 }