Add dedicated SimilarArtists call

core/lastfm/client.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"strconv"
 )
 
 const (
@@ -27,14 +28,10 @@ type Client struct {
 	hc     HttpClient
 }
 
-// TODO SimilarArtists()
-func (c *Client) ArtistGetInfo(ctx context.Context, name string) (*Artist, error) {
-	params := url.Values{}
-	params.Add("method", "artist.getInfo")
+func (c *Client) makeRequest(params url.Values) (*Response, error) {
 	params.Add("format", "json")
 	params.Add("api_key", c.apiKey)
-	params.Add("artist", name)
-	params.Add("lang", c.lang)
+
 	req, _ := http.NewRequest("GET", apiBaseUrl, nil)
 	req.URL.RawQuery = params.Encode()
 
@@ -55,7 +52,32 @@ func (c *Client) ArtistGetInfo(ctx context.Context, name string) (*Artist, error
 
 	var response Response
 	err = json.Unmarshal(data, &response)
-	return &response.Artist, err
+
+	return &response, err
+}
+
+func (c *Client) ArtistGetInfo(ctx context.Context, name string) (*Artist, error) {
+	params := url.Values{}
+	params.Add("method", "artist.getInfo")
+	params.Add("artist", name)
+	params.Add("lang", c.lang)
+	response, err := c.makeRequest(params)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Artist, nil
+}
+
+func (c *Client) ArtistGetSimilar(ctx context.Context, name string, limit int) ([]Artist, error) {
+	params := url.Values{}
+	params.Add("method", "artist.getSimilar")
+	params.Add("artist", name)
+	params.Add("limit", strconv.Itoa(limit))
+	response, err := c.makeRequest(params)
+	if err != nil {
+		return nil, err
+	}
+	return response.SimilarArtists.Artists, nil
 }
 
 func (c *Client) parseError(data []byte) error {

core/lastfm/client_test.go

@@ -21,7 +21,7 @@ var _ = Describe("Client", func() {
 		client = NewClient("API_KEY", "pt", httpClient)
 	})
 
-	Describe("ArtistInfo", func() {
+	Describe("ArtistGetInfo", func() {
 		It("returns an artist for a successful response", func() {
 			f, _ := os.Open("tests/fixtures/lastfm.artist.getinfo.json")
 			httpClient.res = http.Response{Body: f, StatusCode: 200}
@@ -60,6 +60,46 @@ var _ = Describe("Client", func() {
 		})
 
 	})
+
+	Describe("ArtistGetSimilar", func() {
+		It("returns an artist for a successful response", func() {
+			f, _ := os.Open("tests/fixtures/lastfm.artist.getsimilar.json")
+			httpClient.res = http.Response{Body: f, StatusCode: 200}
+
+			artists, err := client.ArtistGetSimilar(context.TODO(), "U2", 2)
+			Expect(err).To(BeNil())
+			Expect(len(artists)).To(Equal(2))
+			Expect(httpClient.savedRequest.URL.String()).To(Equal(apiBaseUrl + "?api_key=API_KEY&artist=U2&format=json&limit=2&method=artist.getSimilar"))
+		})
+
+		It("fails if Last.FM returns an error", func() {
+			httpClient.res = http.Response{
+				Body:       ioutil.NopCloser(bytes.NewBufferString(`{"error":3,"message":"Invalid Method - No method with that name in this package"}`)),
+				StatusCode: 400,
+			}
+
+			_, err := client.ArtistGetSimilar(context.TODO(), "U2", 2)
+			Expect(err).To(MatchError("last.fm error(3): Invalid Method - No method with that name in this package"))
+		})
+
+		It("fails if HttpClient.Do() returns error", func() {
+			httpClient.err = errors.New("generic error")
+
+			_, err := client.ArtistGetSimilar(context.TODO(), "U2", 2)
+			Expect(err).To(MatchError("generic error"))
+		})
+
+		It("fails if returned body is not a valid JSON", func() {
+			httpClient.res = http.Response{
+				Body:       ioutil.NopCloser(bytes.NewBufferString(`<xml>NOT_VALID_JSON</xml>`)),
+				StatusCode: 200,
+			}
+
+			_, err := client.ArtistGetSimilar(context.TODO(), "U2", 2)
+			Expect(err).To(MatchError("invalid character '<' looking for beginning of value"))
+		})
+
+	})
 })
 
 type fakeHttpClient struct {

core/lastfm/responses.go

@@ -1,7 +1,8 @@
 package lastfm
 
 type Response struct {
-	Artist Artist `json:"artist"`
+	Artist         Artist         `json:"artist"`
+	SimilarArtists SimilarArtists `json:"similarartists"`
 }
 
 type Artist struct {
@@ -14,15 +15,17 @@ type Artist struct {
 		Listeners string `json:"listeners"`
 		Plays     string `json:"plays"`
 	} `json:"stats"`
-	Similar struct {
-		Artists []Artist `json:"artist"`
-	} `json:"similar"`
-	Tags struct {
+	Similar SimilarArtists `json:"similar"`
+	Tags    struct {
 		Tag []ArtistTag `json:"tag"`
 	} `json:"tags"`
 	Bio ArtistBio `json:"bio"`
 }
 
+type SimilarArtists struct {
+	Artists []Artist `json:"artist"`
+}
+
 type ArtistImage struct {
 	URL  string `json:"#text"`
 	Size string `json:"size"`

core/lastfm/responses_test.go

@@ -28,6 +28,19 @@ var _ = Describe("LastFM responses", func() {
 		})
 	})
 
+	Describe("SimilarArtists", func() {
+		It("parses the response correctly", func() {
+			var resp Response
+			body, _ := ioutil.ReadFile("tests/fixtures/lastfm.artist.getsimilar.json")
+			err := json.Unmarshal(body, &resp)
+			Expect(err).To(BeNil())
+
+			Expect(resp.SimilarArtists.Artists).To(HaveLen(2))
+			Expect(resp.SimilarArtists.Artists[0].Name).To(Equal("Passengers"))
+			Expect(resp.SimilarArtists.Artists[1].Name).To(Equal("INXS"))
+		})
+	})
+
 	Describe("Error", func() {
 		It("parses the error response correctly", func() {
 			var error Error