Update EMAFilterTest.java

Author: Shreya123714

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

@@ -1,56 +1,45 @@
 package com.thealgorithms.audiofilters;
 
-/**
- * Exponential Moving Average (EMA) Filter for smoothing audio signals.
- *
- * <p>
- * This filter applies an exponential moving average to a sequence of audio
- * signal values, making it useful for smoothing out rapid fluctuations.
- * The smoothing factor (alpha) controls the degree of smoothing.
- *
- * <p>
- * Based on the definition from
- * <a href="https://en.wikipedia.org/wiki/Moving_average">Wikipedia link</a>.
- */
-public class EMAFilter {
-
-    private final double alpha;
-    private double emaValue;
-
-    /**
-     * Constructs an EMA filter with a given smoothing factor.
-     *
-     * @param alpha Smoothing factor (0 < alpha <= 1)
-     * @throws IllegalArgumentException if alpha is not in (0, 1]
-     */
-    public EMAFilter(double alpha) {
-        if (alpha <= 0 || alpha > 1) {
-            throw new IllegalArgumentException("Alpha must be between 0 and 1.");
-        }
-        this.alpha = alpha;
-        this.emaValue = 0.0;
+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);
     }
 
-    /**
-     * Applies the EMA filter to an audio signal array.
-     *
-     * @param audioSignal Array of audio samples to process
-     * @return Array of processed (smoothed) samples
-     */
-    public double[] apply(double[] audioSignal) {
-        if (audioSignal.length == 0) {
-            return new double[0];
-        }
-
-        double[] emaSignal = new double[audioSignal.length];
-        emaValue = audioSignal[0];
-        emaSignal[0] = emaValue;
-
-        for (int i = 1; i < audioSignal.length; i++) {
-            emaValue = alpha * audioSignal[i] + (1 - alpha) * emaValue;
-            emaSignal[i] = emaValue;
-        }
-
-        return emaSignal;
+    @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);
+
+        // Maximum smoothing (alpha = 1, output should match input)
+        double[] resultMax = emaFilterMax.apply(audioSignal);
+
+        assertArrayEquals(audioSignal, resultMax, 1e-5);
     }
 }