Add tests for Convolution

DIRECTORY.md

@@ -907,6 +907,7 @@
             * [CeilTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/CeilTest.java)
             * [CollatzConjectureTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/CollatzConjectureTest.java)
             * [CombinationsTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/CombinationsTest.java)
+            * [ConvolutionTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/ConvolutionTest.java)
             * [CrossCorrelationTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/CrossCorrelationTest.java)
             * [DeterminantOfMatrixTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DeterminantOfMatrixTest.java)
             * [DigitalRootTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/maths/DigitalRootTest.java)

src/test/java/com/thealgorithms/maths/ConvolutionTest.java

@@ -0,0 +1,74 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class ConvolutionTest {
+
+    @Test
+    public void testConvolutionBasic() {
+        double[] signalA = {1, 2, 3};
+        double[] signalB = {4, 5, 6};
+        double[] expected = {4, 13, 28, 27, 18}; // Expected output
+
+        double[] result = Convolution.convolution(signalA, signalB);
+
+        assertArrayEquals(expected, result, 1e-9); // Allowing for floating-point precision
+    }
+
+    @Test
+    public void testConvolutionWithZeroElements() {
+        double[] signalA = {0, 0, 0};
+        double[] signalB = {1, 2, 3};
+        double[] expected = {0, 0, 0, 0, 0}; // All values should remain zero
+
+        double[] result = Convolution.convolution(signalA, signalB);
+
+        assertArrayEquals(expected, result, 1e-9);
+    }
+
+    @Test
+    public void testConvolutionSingleElement() {
+        double[] signalA = {2};
+        double[] signalB = {3};
+        double[] expected = {6}; // 2 * 3 = 6
+
+        double[] result = Convolution.convolution(signalA, signalB);
+
+        assertArrayEquals(expected, result, 1e-9);
+    }
+
+    @Test
+    public void testConvolutionWithDifferentSizes() {
+        double[] signalA = {1, 2};
+        double[] signalB = {3, 4, 5};
+        double[] expected = {3, 10, 13, 10}; // Expected output
+
+        double[] result = Convolution.convolution(signalA, signalB);
+
+        assertArrayEquals(expected, result, 1e-9);
+    }
+
+    @Test
+    public void testConvolutionWithNegativeValues() {
+        double[] signalA = {1, -2, 3};
+        double[] signalB = {-1, 2, -3};
+        double[] expected = {-1, 4, -10, 12, -9}; // Expected output
+
+        double[] result = Convolution.convolution(signalA, signalB);
+
+        assertArrayEquals(expected, result, 1e-9);
+    }
+
+    @Test
+    public void testConvolutionWithLargeNumbers() {
+        double[] signalA = {1e6, 2e6};
+        double[] signalB = {3e6, 4e6};
+        double[] expected = {3e12, 1e13, 8e12}; // Expected output with large numbers
+
+        double[] result = Convolution.convolution(signalA, signalB);
+
+        assertArrayEquals(expected, result, 1e-9);
+    }
+}