def test_insert_hash(self):
    'Test _insert_hash returns correct filenames with provided hashes.'
    self.assertEqual(build._insert_hash('file.js', '123456'), 'file.123456.js')
    self.assertEqual(build._insert_hash('path/to/file.js', '654321'), 'path/to/file.654321.js')
    self.assertEqual(build._insert_hash('file.min.js', 'abcdef'), 'file.min.abcdef.js')
    self.assertEqual(build._insert_hash('path/to/file.min.js', 'fedcba'), 'path/to/file.min.fedcba.js')
Test _insert_hash returns correct filenames with provided hashes.
def test_insert_hash(self):
    
    self.assertEqual(build._insert_hash('file.js', '123456'), 'file.123456.js')
    self.assertEqual(build._insert_hash('path/to/file.js', '654321'), 'path/to/file.654321.js')
    self.assertEqual(build._insert_hash('file.min.js', 'abcdef'), 'file.min.abcdef.js')
    self.assertEqual(build._insert_hash('path/to/file.min.js', 'fedcba'), 'path/to/file.min.fedcba.js')