Improve TrieImp.java comments & enhance readability (#5526)

src/test/java/com/thealgorithms/datastructures/trees/TrieImpTest.java

@@ -0,0 +1,76 @@
+package com.thealgorithms.datastructures.trees;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class TrieImpTest {
+    private TrieImp trie;
+
+    @BeforeEach
+    public void setUp() {
+        trie = new TrieImp();
+    }
+
+    @Test
+    public void testInsertAndSearchBasic() {
+        String word = "hello";
+        trie.insert(word);
+        assertTrue(trie.search(word), "Search should return true for an inserted word.");
+    }
+
+    @Test
+    public void testSearchNonExistentWord() {
+        String word = "world";
+        assertFalse(trie.search(word), "Search should return false for a non-existent word.");
+    }
+
+    @Test
+    public void testInsertAndSearchMultipleWords() {
+        String word1 = "cat";
+        String word2 = "car";
+        trie.insert(word1);
+        trie.insert(word2);
+
+        assertTrue(trie.search(word1), "Search should return true for an inserted word.");
+        assertTrue(trie.search(word2), "Search should return true for another inserted word.");
+        assertFalse(trie.search("dog"), "Search should return false for a word not in the Trie.");
+    }
+
+    @Test
+    public void testDeleteExistingWord() {
+        String word = "remove";
+        trie.insert(word);
+        assertTrue(trie.delete(word), "Delete should return true for an existing word.");
+        assertFalse(trie.search(word), "Search should return false after deletion.");
+    }
+
+    @Test
+    public void testDeleteNonExistentWord() {
+        String word = "nonexistent";
+        assertFalse(trie.delete(word), "Delete should return false for a non-existent word.");
+    }
+
+    @Test
+    public void testInsertAndSearchPrefix() {
+        String prefix = "pre";
+        String word = "prefix";
+        trie.insert(prefix);
+        trie.insert(word);
+
+        assertTrue(trie.search(prefix), "Search should return true for an inserted prefix.");
+        assertTrue(trie.search(word), "Search should return true for a word with the prefix.");
+        assertFalse(trie.search("pref"), "Search should return false for a prefix that is not a full word.");
+    }
+
+    @Test
+    public void testIsValidWord() {
+        assertTrue(TrieImp.isValid("validword"), "Word should be valid (only lowercase letters).");
+        assertFalse(TrieImp.isValid("InvalidWord"), "Word should be invalid (contains uppercase letters).");
+        assertFalse(TrieImp.isValid("123abc"), "Word should be invalid (contains numbers).");
+        assertFalse(TrieImp.isValid("hello!"), "Word should be invalid (contains special characters).");
+        assertFalse(TrieImp.isValid(""), "Empty string should be invalid.");
+    }
+}