add initial Last.FM tests (#329)

* Move model into separate file

* Separate Last.FM client and scrobbler

* Use separate Last.FM client and scrobbler

* Fix playcount attribute name

* Add initial test for Last.FM client

scrobble/lastfm/client_test.go

@@ -0,0 +1,161 @@
+package lastfm
+
+import (
+	"context"
+	"crypto/md5"
+	"crypto/tls"
+	_ "embed"
+	"encoding/xml"
+	"fmt"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func httpClientMock(handler http.Handler) (http.Client, func()) {
+	server := httptest.NewTLSServer(handler)
+	client := http.Client{
+		Transport: &http.Transport{
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				return net.Dial(network, server.Listener.Addr().String())
+			},
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: true, //nolint:gosec
+			},
+		},
+	}
+
+	return client, server.Close
+}
+
+//go:embed testdata/artist_get_info_response.xml
+var artistGetInfoResponse string
+
+func TestArtistGetInfo(t *testing.T) {
+	// arrange
+	require := require.New(t)
+	httpClient, shutdown := httpClientMock(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(http.MethodGet, r.Method)
+		require.Equal(url.Values{
+			"method":  []string{"artist.getInfo"},
+			"api_key": []string{"apiKey1"},
+			"artist":  []string{"Artist 1"},
+		}, r.URL.Query())
+		require.Equal("/2.0/", r.URL.Path)
+		require.Equal(baseURL, "https://"+r.Host+r.URL.Path)
+
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(artistGetInfoResponse))
+	}))
+	defer shutdown()
+
+	client := Client{&httpClient}
+
+	// act
+	actual, err := client.ArtistGetInfo("apiKey1", "Artist 1")
+
+	// assert
+	require.NoError(err)
+	require.Equal(Artist{
+		XMLName: xml.Name{
+			Local: "artist",
+		},
+		Name:       "Artist 1",
+		MBID:       "366c1119-ec4f-4312-b729-a5637d148e3e",
+		Streamable: "0",
+		Stats: struct {
+			Listeners string `xml:"listeners"`
+			Playcount string `xml:"playcount"`
+		}{
+			Listeners: "1",
+			Playcount: "2",
+		},
+		URL: "https://www.last.fm/music/Artist+1",
+		Image: []ArtistImage{
+			{
+				Size: "small",
+				Text: "https://last.fm/artist-1-small.png",
+			},
+		},
+		Bio: ArtistBio{
+			Published: "13 May 2023, 00:24",
+			Summary:   "Summary",
+			Content:   "Content",
+		},
+		Similar: struct {
+			Artists []Artist `xml:"artist"`
+		}{
+			Artists: []Artist{
+				{
+					XMLName: xml.Name{
+						Local: "artist",
+					},
+					Name: "Similar Artist 1",
+					URL:  "https://www.last.fm/music/Similar+Artist+1",
+					Image: []ArtistImage{
+						{
+							Size: "small",
+							Text: "https://last.fm/similar-artist-1-small.png",
+						},
+					},
+				},
+			},
+		},
+		Tags: struct {
+			Tag []ArtistTag `xml:"tag"`
+		}{
+			Tag: []ArtistTag{
+				{
+					Name: "tag1",
+					URL:  "https://www.last.fm/tag/tag1",
+				},
+			},
+		},
+	}, actual)
+}
+
+func TestArtistGetInfo_clientRequestFails(t *testing.T) {
+	// arrange
+	require := require.New(t)
+	httpClient, shutdown := httpClientMock(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		require.Equal(http.MethodGet, r.Method)
+		require.Equal(url.Values{
+			"method":  []string{"artist.getInfo"},
+			"api_key": []string{"apiKey1"},
+			"artist":  []string{"Artist 1"},
+		}, r.URL.Query())
+		require.Equal("/2.0/", r.URL.Path)
+		require.Equal(baseURL, "https://"+r.Host+r.URL.Path)
+
+		w.WriteHeader(http.StatusInternalServerError)
+	}))
+	defer shutdown()
+
+	client := Client{&httpClient}
+
+	// act
+	actual, err := client.ArtistGetInfo("apiKey1", "Artist 1")
+
+	// assert
+	require.Error(err)
+	require.Zero(actual)
+}
+
+func TestGetParamSignature(t *testing.T) {
+	params := url.Values{}
+	params.Add("ccc", "CCC")
+	params.Add("bbb", "BBB")
+	params.Add("aaa", "AAA")
+	params.Add("ddd", "DDD")
+	actual := getParamSignature(params, "secret")
+	expected := fmt.Sprintf("%x", md5.Sum([]byte(
+		"aaaAAAbbbBBBcccCCCdddDDDsecret",
+	)))
+	if actual != expected {
+		t.Errorf("expected %x, got %s", expected, actual)
+	}
+}