Ensure test files are executed in alphabetical order

lib/codecept.js

@@ -184,6 +184,8 @@ class Codecept {
       }
     }
 
+    this.testFiles.sort()
+
     if (this.opts.shuffle) {
       this.testFiles = this.shuffle(this.testFiles)
     }

test/unit/alphabetical_order_test.js

@@ -0,0 +1,84 @@
+const expect = require('chai').expect
+const Codecept = require('../../lib/codecept')
+const path = require('path')
+const fs = require('fs')
+
+describe('Test Files Alphabetical Order', () => {
+  let codecept
+  const tempDir = path.join(__dirname, '../data/sandbox/configs/alphabetical_order')
+  const config = {
+    tests: `${tempDir}/*_test.js`,
+    gherkin: { features: null },
+    output: './output',
+    hooks: [],
+  }
+
+  before(() => {
+    if (!fs.existsSync(tempDir)) {
+      fs.mkdirSync(tempDir, { recursive: true })
+    }
+
+    fs.writeFileSync(
+      path.join(tempDir, 'zzz_test.js'),
+      `
+        Feature('Test');
+        Scenario('zzz test', () => {});
+      `,
+    )
+    fs.writeFileSync(
+      path.join(tempDir, 'aaa_test.js'),
+      `
+        Feature('Test');
+        Scenario('aaa test', () => {});
+      `,
+    )
+    fs.writeFileSync(
+      path.join(tempDir, 'mmm_test.js'),
+      `
+        Feature('Test');
+        Scenario('mmm test', () => {});
+      `,
+    )
+  })
+
+  after(() => {
+    const files = ['zzz_test.js', 'aaa_test.js', 'mmm_test.js']
+    files.forEach(file => {
+      const filePath = path.join(tempDir, file)
+      if (fs.existsSync(filePath)) {
+        fs.unlinkSync(filePath)
+      }
+    })
+  })
+
+  beforeEach(() => {
+    codecept = new Codecept(config, {})
+    codecept.init(path.join(__dirname, '../data/sandbox'))
+  })
+
+  it('should sort test files alphabetically after loading', () => {
+    codecept.loadTests()
+
+    if (codecept.testFiles.length === 0) {
+      console.log('No test files found, skipping test')
+      return
+    }
+
+    const filenames = codecept.testFiles.map(filePath => path.basename(filePath))
+
+    const sortedFilenames = [...filenames].sort()
+
+    expect(filenames).to.deep.equal(sortedFilenames)
+
+    const aaaIndex = filenames.findIndex(f => f.includes('aaa_test.js'))
+    const mmmIndex = filenames.findIndex(f => f.includes('mmm_test.js'))
+    const zzzIndex = filenames.findIndex(f => f.includes('zzz_test.js'))
+
+    expect(aaaIndex).to.be.greaterThan(-1)
+    expect(mmmIndex).to.be.greaterThan(-1)
+    expect(zzzIndex).to.be.greaterThan(-1)
+
+    expect(aaaIndex).to.be.lessThan(mmmIndex, 'aaa_test.js should come before mmm_test.js')
+    expect(mmmIndex).to.be.lessThan(zzzIndex, 'mmm_test.js should come before zzz_test.js')
+  })
+})