feat: refactor and test tools steps utilities (#42693)

tools/challenge-helper-scripts/helpers/get-last-step-file-content.test.js

@@ -0,0 +1,57 @@
+const mock = require('mock-fs');
+const { getLastStepFileContent } = require('./get-last-step-file-content');
+
+jest.mock('./get-project-path', () => {
+  return {
+    getProjectPath: jest.fn(() => 'mock-project/')
+  };
+});
+
+jest.mock('../utils', () => {
+  return {
+    getChallengeSeeds: jest.fn(() => {
+      return {
+        lorem: 'ipsum'
+      };
+    })
+  };
+});
+
+describe('getLastStepFileContent helper', () => {
+  it('should throw if last step count does not match with numbers of steps', () => {
+    mock({
+      'mock-project/': {
+        'part-001.md': 'Lorem ipsum...',
+        'part-004.md': 'Lorem ipsum...',
+        'final.md': 'Lorem ipsum...'
+      }
+    });
+
+    expect(() => {
+      getLastStepFileContent();
+    }).toThrow();
+
+    mock.restore();
+  });
+
+  it('should return information if steps count is correct', () => {
+    mock({
+      'mock-project': {
+        'part-001.md': 'Lorem ipsum...',
+        'part-002.md': 'Lorem ipsum...',
+        'final.md': 'Lorem ipsum...'
+      }
+    });
+
+    const expected = {
+      nextStepNum: 3,
+      challengeSeeds: {
+        lorem: 'ipsum'
+      }
+    };
+
+    expect(getLastStepFileContent()).toEqual(expected);
+
+    mock.restore();
+  });
+});