add param parsing methods

related: #41

server/ctrlsubsonic/params/params_test.go

@@ -0,0 +1,55 @@
+package params
+
+import (
+	"errors"
+	"testing"
+)
+
+func TestParseID(t *testing.T) {
+	tcases := []struct {
+		param    string
+		expType  IDType
+		expValue int
+		expErr   error
+	}{
+		{param: "al-45", expType: IDTypeAlbum, expValue: 45},
+		{param: "ar-2", expType: IDTypeArtist, expValue: 2},
+		{param: "tr-43", expType: IDTypeTrack, expValue: 43},
+		{param: "xx-1", expErr: ErrIDInvalid},
+		{param: "al-howdy", expErr: ErrIDNotAnInt},
+	}
+	for _, tcase := range tcases {
+		t.Run(tcase.param, func(t *testing.T) {
+			act, err := parseID(tcase.param)
+			if err != nil && !errors.Is(err, tcase.expErr) {
+				t.Fatalf("expected err %q, got %q", tcase.expErr, err)
+			}
+			if act.Value != tcase.expValue {
+				t.Errorf("expected value %d, got %d", tcase.expValue, act.Value)
+			}
+			if act.Type != tcase.expType {
+				t.Errorf("expected type %v, got %v", tcase.expType, act.Type)
+			}
+		})
+	}
+}
+
+// TODO?
+func TestGet(t *testing.T)             {}
+func TestGetFirst(t *testing.T)        {}
+func TestGetOr(t *testing.T)           {}
+func TestGetList(t *testing.T)         {}
+func TestGetFirstList(t *testing.T)    {}
+func TestGetOrList(t *testing.T)       {}
+func TestGetInt(t *testing.T)          {}
+func TestGetFirstInt(t *testing.T)     {}
+func TestGetOrInt(t *testing.T)        {}
+func TestGetIntList(t *testing.T)      {}
+func TestGetFirstIntList(t *testing.T) {}
+func TestGetOrIntList(t *testing.T)    {}
+func TestGetID(t *testing.T)           {}
+func TestGetFirstID(t *testing.T)      {}
+func TestGetOrID(t *testing.T)         {}
+func TestGetIDList(t *testing.T)       {}
+func TestGetFirstIDList(t *testing.T)  {}
+func TestGetOrIDList(t *testing.T)     {}