Create RegularExpressionMatchingTest.java

Author: kokatesaurabh

src/test/java/com/thealgorithms/RegularExpressionMatchingTest.java

@@ -0,0 +1,122 @@
+package com.thealgorithms.dynamicprogramming;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for RegularExpressionMatching algorithm.
+ * 
+ * <p>
+ * For more information about regular expression matching:
+ * @see <a href="https://en.wikipedia.org/wiki/Regular_expression">Regular Expression</a>
+ * @see <a href="https://leetcode.com/problems/regular-expression-matching/">LeetCode Problem 10</a>
+ */
+class RegularExpressionMatchingTest {
+
+    @Test
+    void testBasicMatching() {
+        assertTrue(RegularExpressionMatching.isMatch("abc", "abc"));
+        assertFalse(RegularExpressionMatching.isMatch("abc", "abcd"));
+        assertFalse(RegularExpressionMatching.isMatch("abcd", "abc"));
+    }
+
+    @Test
+    void testDotWildcard() {
+        assertTrue(RegularExpressionMatching.isMatch("abc", "a.c"));
+        assertTrue(RegularExpressionMatching.isMatch("axc", "a.c"));
+        assertFalse(RegularExpressionMatching.isMatch("abc", "a.."));
+        assertTrue(RegularExpressionMatching.isMatch("abc", "..."));
+        assertFalse(RegularExpressionMatching.isMatch("ab", "..."));
+    }
+
+    @Test
+    void testStarQuantifier() {
+        assertTrue(RegularExpressionMatching.isMatch("aa", "a*"));
+        assertTrue(RegularExpressionMatching.isMatch("aaa", "a*"));
+        assertTrue(RegularExpressionMatching.isMatch("", "a*"));
+        assertFalse(RegularExpressionMatching.isMatch("b", "a*"));
+        assertTrue(RegularExpressionMatching.isMatch("aab", "c*a*b"));
+        assertTrue(RegularExpressionMatching.isMatch("b", "c*a*b"));
+    }
+
+    @Test
+    void testDotStarCombination() {
+        assertTrue(RegularExpressionMatching.isMatch("abc", ".*"));
+        assertTrue(RegularExpressionMatching.isMatch("xyz", ".*"));
+        assertTrue(RegularExpressionMatching.isMatch("", ".*"));
+        assertTrue(RegularExpressionMatching.isMatch("abc123", ".*"));
+        assertTrue(RegularExpressionMatching.isMatch("abc", "a.*c"));
+        assertTrue(RegularExpressionMatching.isMatch("axxxc", "a.*c"));
+        assertFalse(RegularExpressionMatching.isMatch("abc", "a.*d"));
+    }
+
+    @Test
+    void testComplexPatterns() {
+        assertTrue(RegularExpressionMatching.isMatch("mississippi", "mis*is*ip*."));
+        assertTrue(RegularExpressionMatching.isMatch("mississippi", "mis*is*p*."));
+        assertFalse(RegularExpressionMatching.isMatch("mississippi", "mis*is*ip*.."));
+        assertTrue(RegularExpressionMatching.isMatch("a", "a*a*a*"));
+        assertTrue(RegularExpressionMatching.isMatch("aaa", "a*a*a*"));
+        assertTrue(RegularExpressionMatching.isMatch("", "a*b*c*"));
+    }
+
+    @Test
+    void testEdgeCases() {
+        assertTrue(RegularExpressionMatching.isMatch("", ""));
+        assertTrue(RegularExpressionMatching.isMatch("", "a*"));
+        assertTrue(RegularExpressionMatching.isMatch("", ".*"));
+        assertFalse(RegularExpressionMatching.isMatch("", "a"));
+        assertFalse(RegularExpressionMatching.isMatch("", "."));
+        assertTrue(RegularExpressionMatching.isMatch("a", "a"));
+        assertTrue(RegularExpressionMatching.isMatch("a", "."));
+        assertFalse(RegularExpressionMatching.isMatch("a", "b"));
+        assertFalse(RegularExpressionMatching.isMatch("a", "aa"));
+    }
+
+    @Test
+    void testInvalidInputs() {
+        assertThrows(IllegalArgumentException.class, 
+            () -> RegularExpressionMatching.isMatch(null, "pattern"));
+        assertThrows(IllegalArgumentException.class, 
+            () -> RegularExpressionMatching.isMatch("string", null));
+        assertThrows(IllegalArgumentException.class, 
+            () -> RegularExpressionMatching.isMatch(null, null));
+        assertThrows(IllegalArgumentException.class, 
+            () -> RegularExpressionMatching.isMatch("test", "*abc"));
+        assertThrows(IllegalArgumentException.class, 
+            () -> RegularExpressionMatching.isMatch("test", "a**b"));
+    }
+
+    @Test
+    void testIterativeImplementation() {
+        assertTrue(RegularExpressionMatching.isMatchIterative("aa", "a*"));
+        assertTrue(RegularExpressionMatching.isMatchIterative("ab", ".*"));
+        assertFalse(RegularExpressionMatching.isMatchIterative("aa", "a"));
+        assertTrue(RegularExpressionMatching.isMatchIterative("aab", "c*a*b"));
+        
+        String[] testStrings = {"", "a", "aa", "ab", "aaa", "aab"};
+        String[] testPatterns = {"", "a", "a*", ".*", "a.b", "c*a*b"};
+        
+        for (String string : testStrings) {
+            for (String patternString : testPatterns) {
+                if (!patternString.isEmpty() && patternString.charAt(0) != '*') {
+                    boolean recursiveResult = RegularExpressionMatching.isMatch(string, patternString);
+                    boolean iterativeResult = RegularExpressionMatching.isMatchIterative(string, patternString);
+                    assertTrue(recursiveResult == iterativeResult);
+                }
+            }
+        }
+    }
+
+    @Test
+    void testLeetCodeExamples() {
+        assertFalse(RegularExpressionMatching.isMatch("aa", "a"));
+        assertTrue(RegularExpressionMatching.isMatch("aa", "a*"));
+        assertTrue(RegularExpressionMatching.isMatch("ab", ".*"));
+        assertTrue(RegularExpressionMatching.isMatch("aab", "c*a*b"));
+        assertFalse(RegularExpressionMatching.isMatch("mississippi", "mis*is*p*."));
+    }
+}