add subsequence tests

Author: deadem

src/_Problems_/get_subsequence/index.js

@@ -24,7 +24,6 @@ let getSubesequence = (str) => {
     return result;
 }
 
-
-let subsequence = getSubesequence('abc');
-console.log(subsequence);
-
+module.exports = {
+  getSubesequence,
+};

src/_Problems_/get_subsequence/subsequence.test.js

@@ -0,0 +1,19 @@
+const { getSubesequence } = require('.');
+
+describe('GetSubesequence', () => {
+  it('Sequence of abc', () => {
+    expect(getSubesequence('abc').sort()).toEqual([ '', 'a', 'ab', 'abc', 'ac', 'b', 'bc', 'c' ]);
+  });
+
+  it('Sequence of bc', () => {
+    expect(getSubesequence('bc').sort()).toEqual(['', 'b', 'bc', 'c']);
+  });
+
+  it('Sequence of c', () => {
+    expect(getSubesequence('c').sort()).toEqual(['', 'c']);
+  });
+
+  it('Sequence of empty', () => {
+    expect(getSubesequence('').sort()).toEqual(['']);
+  });
+});