Add unit test for EditDistance (#6108)

src/test/java/com/thealgorithms/dynamicprogramming/EditDistanceTest.java

@@ -1,7 +1,9 @@
 package com.thealgorithms.dynamicprogramming;
 
+import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
 
@@ -12,4 +14,91 @@ public class EditDistanceTest {
     void testMinDistance(String str1, String str2, int expected) {
         assertEquals(expected, EditDistance.minDistance(str1, str2));
     }
+
+    @Test
+    public void testEditDistanceBothEmptyStrings() {
+        assertEquals(0, EditDistance.editDistance("", ""));
+    }
+
+    @Test
+    public void testEditDistanceOneEmptyString() {
+        assertEquals(5, EditDistance.editDistance("", "hello"));
+        assertEquals(7, EditDistance.editDistance("worldly", ""));
+    }
+
+    @Test
+    public void testEditDistanceOneEmptyStringMemoization() {
+        int[][] storage = new int[1][6];
+        assertAll("String assertions",
+            ()
+                -> assertEquals(5, EditDistance.editDistance("", "hello", storage)),
+            () -> assertEquals(0, storage[0][0]), () -> assertEquals(0, storage[0][1]), () -> assertEquals(0, storage[0][2]), () -> assertEquals(0, storage[0][3]), () -> assertEquals(0, storage[0][4]), () -> assertEquals(5, storage[0][5]));
+    }
+
+    @Test
+    public void testEditDistanceEqualStrings() {
+        assertEquals(0, EditDistance.editDistance("test", "test"));
+        assertEquals(0, EditDistance.editDistance("abc", "abc"));
+    }
+
+    @Test
+    public void testEditDistanceEqualStringsMemoization() {
+        int[][] storage = new int[4][4];
+        assertAll("String assertions",
+            ()
+                -> assertEquals(0, EditDistance.editDistance("abc", "abc", storage)),
+            ()
+                -> assertEquals(0, storage[0][0]),
+            ()
+                -> assertEquals(0, storage[0][1]),
+            ()
+                -> assertEquals(0, storage[0][2]),
+            ()
+                -> assertEquals(0, storage[0][3]),
+            ()
+                -> assertEquals(0, storage[1][0]),
+            ()
+                -> assertEquals(0, storage[1][1]),
+            ()
+                -> assertEquals(0, storage[1][2]),
+            ()
+                -> assertEquals(0, storage[1][3]),
+            ()
+                -> assertEquals(0, storage[2][0]),
+            () -> assertEquals(0, storage[2][1]), () -> assertEquals(0, storage[2][2]), () -> assertEquals(0, storage[2][3]), () -> assertEquals(0, storage[3][0]), () -> assertEquals(0, storage[3][1]), () -> assertEquals(0, storage[3][2]), () -> assertEquals(0, storage[3][3]));
+    }
+
+    @Test
+    public void testEditDistanceOneCharacterDifference() {
+        assertEquals(1, EditDistance.editDistance("cat", "bat"));
+        assertEquals(1, EditDistance.editDistance("cat", "cats"));
+        assertEquals(1, EditDistance.editDistance("cats", "cat"));
+    }
+
+    @Test
+    public void testEditDistanceOneCharacterDifferenceMemoization() {
+        int[][] storage = new int[3][3];
+        assertAll("All assertions",
+            ()
+                -> assertEquals(1, EditDistance.editDistance("at", "it", storage)),
+            ()
+                -> assertEquals(0, storage[0][0]),
+            ()
+                -> assertEquals(1, storage[0][1]),
+            () -> assertEquals(2, storage[0][2]), () -> assertEquals(1, storage[1][0]), () -> assertEquals(0, storage[1][1]), () -> assertEquals(1, storage[1][2]), () -> assertEquals(2, storage[2][0]), () -> assertEquals(1, storage[2][1]), () -> assertEquals(1, storage[2][2]));
+    }
+
+    @Test
+    public void testEditDistanceGeneralCases() {
+        assertEquals(3, EditDistance.editDistance("kitten", "sitting"));
+        assertEquals(2, EditDistance.editDistance("flaw", "lawn"));
+        assertEquals(5, EditDistance.editDistance("intention", "execution"));
+    }
+
+    @Test
+    public void testEditDistanceGeneralCasesMemoization() {
+        int[][] storage = new int[7][8];
+        assertEquals(3, EditDistance.editDistance("kitten", "sitting", storage));
+        assertAll("All assertions", () -> assertEquals(0, storage[0][0]), () -> assertEquals(3, storage[6][7]));
+    }
 }