Add Exponential Moving Average Filter (#6075)

src/test/java/com/thealgorithms/audiofilters/EMAFilterTest.java

@@ -0,0 +1,41 @@
+package com.thealgorithms.audiofilters;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class EMAFilterTest {
+
+    @Test
+    public void testApplyBasicSignal() {
+        EMAFilter emaFilter = new EMAFilter(0.2);
+        double[] audioSignal = {0.1, 0.5, 0.8, 0.6, 0.3, 0.9, 0.4};
+        double[] expectedOutput = {0.1, 0.18, 0.304, 0.3632, 0.35056, 0.460448, 0.4483584};
+        double[] result = emaFilter.apply(audioSignal);
+        assertArrayEquals(expectedOutput, result, 1e-5);
+    }
+
+    @Test
+    public void testApplyEmptySignal() {
+        EMAFilter emaFilter = new EMAFilter(0.2);
+        double[] audioSignal = {};
+        double[] expectedOutput = {};
+        double[] result = emaFilter.apply(audioSignal);
+        assertArrayEquals(expectedOutput, result);
+    }
+
+    @Test
+    public void testAlphaBounds() {
+        EMAFilter emaFilterMin = new EMAFilter(0.01);
+        EMAFilter emaFilterMax = new EMAFilter(1.0);
+        double[] audioSignal = {1.0, 1.0, 1.0, 1.0};
+
+        // Minimal smoothing (alpha close to 0)
+        double[] resultMin = emaFilterMin.apply(audioSignal);
+        assertArrayEquals(audioSignal, resultMin, 1e-5);
+
+        // Maximum smoothing (alpha = 1, output should match input)
+        double[] resultMax = emaFilterMax.apply(audioSignal);
+        assertArrayEquals(audioSignal, resultMax, 1e-5);
+    }
+}