Remove unused code from Synthesizer.Play

After recent refactorings some code was no longer needed.

audio/synth.go

@@ -94,28 +94,20 @@ func (c *channel) moveToNextNote(sfx SoundEffect) {
 }
 
 func (s *Synthesizer) Play(sfxNo, ch, offset, length int) {
-	if sfxNo == -2 {
-		s.disableLooping(ch)
+	if ch < -1 || ch > 3 {
 		return
 	}
 
-	if ch >= -2 && ch <= 3 {
-		s.Stop(sfxNo)
+	if sfxNo < 0 || sfxNo > maxSfxNo {
+		return
 	}
 
+	s.Stop(sfxNo)
+
 	if ch == -1 {
 		ch = s.findAvailableChannel()
 	}
 
-	if ch < 0 || ch > 3 {
-		return
-	}
-
-	if sfxNo == -1 {
-		s.channels[ch].playing = false
-		return
-	}
-
 	offset = pi.MidInt(offset, 0, 31)
 
 	s.channels[ch].playing = true
@@ -178,19 +170,6 @@ func (s *Synthesizer) StopLoop(channel int) {
 	}
 }
 
-func (s *Synthesizer) disableLooping(ch int) {
-	if ch == -1 || ch == -2 {
-		for i := range s.channels {
-			s.channels[i].loopingDisabled = true
-		}
-		return
-	}
-
-	if ch >= 0 && ch <= 0 {
-		s.channels[ch].loopingDisabled = true
-	}
-}
-
 func (s *Synthesizer) findAvailableChannel() int {
 	for i, c := range s.channels {
 		if !c.playing {

audio/synth_test.go

@@ -595,6 +595,30 @@ func TestSynthesizer_PlayStop(t *testing.T) {
 		}
 	})
 
+	t.Run("should not stop playing sfx when sfx is invalid", func(t *testing.T) {
+		sfxNumbers := []int{math.MinInt, -1, maxSfxNo + 1, math.MaxInt}
+
+		for _, sfxNo := range sfxNumbers {
+			testName := fmt.Sprintf("%d", sfxNo)
+			t.Run(testName, func(t *testing.T) {
+				synth := &audio.Synthesizer{}
+				var e audio.SoundEffect
+				e.Speed = 1
+				e.Notes[0].Volume = audio.VolumeLoudest
+				synth.SetSfx(0, e)
+
+				synth.Play(0, 0, 0, 1)
+				// when
+				synth.Play(sfxNo, 0, 0, 1)
+				// then
+				stat := synth.Stat()
+				assert.Equal(t, 0, stat.Sfx[0])
+				// and
+				assertNotSilence(t, readSamples(synth, durationOfNoteWhenSpeedIsOne))
+			})
+		}
+	})
+
 	sfxOffsetLengthTest(t)
 	sfxLoopTest(t)
 	sfxLengthTest(t)