feat: Implement Levenshtein with tests

package.json

@@ -4,7 +4,7 @@
     "description": "",
     "main": "index.js",
     "scripts": {
-        "test": "echo \"Error: no test specified\" && exit 1",
+        "test": "jest",
         "start": "parcel src/index.html --public-url '/app/'"
     },
     "author": "",
@@ -17,10 +17,27 @@
         "react-router-dom": "^4.3.1"
     },
     "devDependencies": {
+        "@types/jest": "^23.3.2",
         "html-webpack-plugin": "3.2.0",
+        "jest": "^23.6.0",
+        "parcel-bundler": "^1.9.7",
+        "ts-jest": "^23.1.4",
         "typescript": "^2.9.2",
         "webpack": "4.17.1",
-        "webpack-cli": "3.1.0",
-        "parcel-bundler": "^1.9.7"
+        "webpack-cli": "3.1.0"
+    },
+    "jest": {
+        "transform": {
+            "^.+\\.tsx?$": "ts-jest"
+        },
+        "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)$",
+        "moduleFileExtensions": [
+            "ts",
+            "tsx",
+            "js",
+            "jsx",
+            "json",
+            "node"
+        ]
     }
 }

src/algorithms/levenshtein/__tests__/levenshtein.test.ts

@@ -0,0 +1,16 @@
+import { lev, levW } from "../";
+
+test("lev(abc, abd) == 1", () => {
+    expect(lev("abc", "abd", 3, 3)).toBe(1);
+    expect(levW("abc", "abd")).toBe(1);
+});
+
+test("lev(abc, abcd) == 1", () => {
+    expect(lev("abc", "abcd", 3, 4)).toBe(1);
+    expect(levW("abc", "abcd")).toBe(1);
+});
+
+test("lev(abcd, bcd) == 1", () => {
+    expect(lev("abcd", "bcd", 4, 3)).toBe(1);
+    expect(levW("abcd", "bcd")).toBe(1);
+});

src/algorithms/levenshtein/index.ts

@@ -0,0 +1,30 @@
+export function one(a: string, b: string, i: number, j: number) {
+    if (a[i] === b[j]) {
+        return 0;
+    }
+
+    return 1;
+}
+
+// Computes the difference between the strings a and b.
+// @a, b: The strings to compare
+// @i, j: From where to compare (a_i and b_j)
+// @ret : The distance in insertions, deletions and changes
+export function lev(a: string, b: string, i: number, j: number) {
+    if (Math.min(i, j) === 0) {
+        return Math.max(i, j);
+    } else {
+        return Math.min(
+            lev(a, b, i - 1, j) + 1,
+            lev(a, b, i, j - 1) + 1,
+            lev(a, b, i - 1, j - 1) + one(a, b, i, j)
+        );
+    }
+};
+
+// Computes the difference between the strings a and b.
+// @a, b: The strings to compare
+// @ret : The distance in insertions, deletions and changes
+export function levW(a: string, b: string) {
+    return lev(a, b, a.length, b.length);
+}

tsconfig.json

@@ -15,7 +15,7 @@
         "noImplicitAny": true,
         "strictNullChecks": true,
         "suppressImplicitAnyIndexErrors": true,
-    "noUnusedLocals": true
+        "noUnusedLocals": true,
     },
     "exclude": [
         "node_modules",