Test SineTone generator

generators/sine_test.go

@@ -0,0 +1,36 @@
+package generators_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/gopxl/beep"
+	"github.com/gopxl/beep/generators"
+	"github.com/gopxl/beep/internal/testtools"
+)
+
+func TestSineTone(t *testing.T) {
+	epsilon := 0.000001
+
+	s, err := generators.SineTone(beep.SampleRate(8000), 400)
+	assert.NoError(t, err)
+
+	// Get a full single phase including the last sample.
+	phaseLength := 8000 / 400
+	samples := testtools.CollectNum(phaseLength+1, s)
+
+	// The sine wave should be 0 at the start, half a phase and at the end of the phase.
+	assert.InDelta(t, 0, samples[phaseLength*0][0], epsilon)
+	assert.InDelta(t, 0, samples[phaseLength*0][1], epsilon)
+	assert.InDelta(t, 0, samples[phaseLength*1/2][0], epsilon)
+	assert.InDelta(t, 0, samples[phaseLength*1/2][1], epsilon)
+	assert.InDelta(t, 0, samples[phaseLength*1][0], epsilon)
+	assert.InDelta(t, 0, samples[phaseLength*1][1], epsilon)
+
+	// The sine wave should be in a peak and trough at 1/4th and 3/4th in the phase respectively.
+	assert.InDelta(t, 1, samples[phaseLength*1/4][0], epsilon)
+	assert.InDelta(t, 1, samples[phaseLength*1/4][1], epsilon)
+	assert.InDelta(t, -1, samples[phaseLength*3/4][0], epsilon)
+	assert.InDelta(t, -1, samples[phaseLength*3/4][1], epsilon)
+}