tests: Levenshtein Distance (dynamic programming solution) (#1114)

CONTRIBUTING.md

@@ -91,7 +91,7 @@ npm test
 If you want save some time and just run a specific test:
 
 ```shell
-# this will run any test file where the filename matches "koch"
+# This will run any test file where the filename contains "koch" (no need to specify folder path)
 npm test -- koch
 ```
 

Dynamic-Programming/LevenshteinDistance.js

@@ -1,6 +1,10 @@
 /**
- * A Dynamic Programming based solution for calculation of the Levenshtein Distance
+ * @function calculateLevenshteinDp
- * https://en.wikipedia.org/wiki/Levenshtein_distance
+ * @description A Dynamic Programming based solution for calculation of the Levenshtein Distance.
+ * @param {String} x - Word to be converted.
+ * @param {String} y - Desired result after operations.
+ * @return {Integer} The Levenshtein distance between x and y.
+ * @see [Levenshtein_distance](https://en.wikipedia.org/wiki/Levenshtein_distance)
  */
 
 function minimum (a, b, c) {
@@ -18,7 +22,7 @@ function costOfSubstitution (x, y) {
 }
 
 // Levenshtein distance between x and y
-function calculate (x, y) {
+function calculateLevenshteinDp (x, y) {
   const dp = new Array(x.length + 1)
   for (let i = 0; i < x.length + 1; i++) {
     dp[i] = new Array(y.length + 1)
@@ -39,4 +43,4 @@ function calculate (x, y) {
   return dp[x.length][y.length]
 }
 
-export { calculate }
+export { calculateLevenshteinDp }

Dynamic-Programming/tests/LevenshteinDistance.test.js

@@ -0,0 +1,19 @@
+import { calculateLevenshteinDp } from '../LevenshteinDistance'
+
+test('Should return the distance counting additions and removals', () => {
+  const from = 'kitten'
+  const to = 'sitting'
+  expect(calculateLevenshteinDp(from, to)).toBe(3)
+})
+
+test('Should return the distance based on replacements in the middle of the strings', () => {
+  const from = 'book'
+  const to = 'back'
+  expect(calculateLevenshteinDp(from, to)).toBe(2)
+})
+
+test('Should return the distance for strings with different length', () => {
+  const from = 'sunday'
+  const to = 'saturday'
+  expect(calculateLevenshteinDp(from, to)).toBe(3)
+})