1 files changed, 66 insertions, 0 deletions
diff --git a/src/test/java/se/lublin/humla/test/MixerTest.java b/src/test/java/se/lublin/humla/test/MixerTest.java
new file mode 100644
index 0000000..43c880b
--- /dev/null
+++ b/src/test/java/se/lublin/humla/test/MixerTest.java
@@ -0,0 +1,66 @@
+package se.lublin.humla.test;
+
+import junit.framework.TestCase;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import se.lublin.humla.audio.BasicClippingShortMixer;
+import se.lublin.humla.audio.IAudioMixer;
+import se.lublin.humla.audio.IAudioMixerSource;
+
+/**
+ * Created by andrew on 16/07/15.
+ */
+public class MixerTest extends TestCase {
+    /**
+     * Tests that mixing order should not affect the output.
+     */
+    public void testMixerCommutativity(IAudioMixer<float[], short[]> mixer) {
+        BasicSource<float[]> pcmA = new BasicSource<>(new float[] { 0.2f, 0.5f, 0.7f }, 3);
+        BasicSource<float[]> pcmB = new BasicSource<>(new float[] { 0.3f, 0.5f, 0.5f }, 3);
+        BasicSource<float[]> pcmC = new BasicSource<>(new float[] { 0.0f, 0.0f, -0.5f }, 3);
+        final short[] outputABC = new short[3];
+        final short[] outputCBA = new short[3];
+
+        List<IAudioMixerSource<float[]>> sourcesABC = new ArrayList<>();
+        sourcesABC.add(pcmA);
+        sourcesABC.add(pcmB);
+        sourcesABC.add(pcmC);
+        List<IAudioMixerSource<float[]>> sourcesCBA = new ArrayList<>();
+        sourcesCBA.add(pcmC);
+        sourcesCBA.add(pcmB);
+        sourcesCBA.add(pcmA);
+
+        mixer.mix(sourcesABC, outputABC, 0, 3);
+        mixer.mix(sourcesCBA, outputCBA, 0, 3);
+
+        for (int i = 0; i < 3; i++) {
+            assertEquals("Mixing should be commutative.", outputABC[i], outputCBA[i]);
+        }
+    }
+
+    public void testBasicClippingShortMixer() {
+        testMixerCommutativity(new BasicClippingShortMixer());
+    }
+
+    private static class BasicSource<T> implements IAudioMixerSource<T> {
+        private T mSamples;
+        private int mLength;
+
+        public BasicSource(T samples, int length) {
+            mSamples = samples;
+            mLength = length;
+        }
+
+        @Override
+        public T getSamples() {
+            return mSamples;
+        }
+
+        @Override
+        public int getNumSamples() {
+            return mLength;
+        }
+    }
+}