Added tests for coloured_diff

Author: domdfcoding

tests/test_diff/modified

@@ -0,0 +1,7 @@
+Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque feugiat,
+lectus et interdum feugiat, magna enim vestibulum diam, a ultrices urna
+odio at magna. Quisque
+ut ullamcorper justo.
+Integer lobortis eros eget diam varius eleifend. Donec
+ornare nisi vel purus aliquet consequat. Ut quis ipsum
+et nunc sodales tristique.

tests/test_diff/original

@@ -0,0 +1,8 @@
+Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+Quisque feugiat, lectus et interdum feugiat, magna enim
+vestibulum diam, a ultrices urna odio at magna. Quisque
+ut ullamcorper justo. Suspendisse ac tincidunt velit.
+Integer lobortis eros eget diam varius eleifend. Donec
+ornare nisi vel purus aliquet consequat. Ut quis ipsum
+et nunc sodales tristique. Maecenas justo libero, semper
+eget feugiat et, aliquam et mauris.

tests/test_utils.py

@@ -17,11 +17,13 @@
 
 # 3rd party
 import pytest
+from pytest_regressions.file_regression import FileRegressionFixture
 
 # this package
 from domdf_python_tools import utils
+from domdf_python_tools.paths import PathPlus
 from domdf_python_tools.testing import testing_boolean_values
-from domdf_python_tools.utils import HasHead, head
+from domdf_python_tools.utils import HasHead, coloured_diff, head
 
 
 def test_pyversion():
@@ -505,3 +507,25 @@ def test_deprecations():
 	assert record[3].message.args == (
 			'list2string', '0.8.0', '1.0.0', "Use 'domdf_python_tools.utils.list2str' instead."
 			)
+
+
+def test_diff(file_regression: FileRegressionFixture):
+	data_dir = PathPlus(__file__).parent / "test_diff"
+	original = data_dir / "original"
+	modified = data_dir / "modified"
+
+	diff = coloured_diff(
+					original.read_lines(),
+					modified.read_lines(),
+					fromfile="original_file.txt",
+					tofile="modified_file.txt",
+					fromfiledate="(original)",
+					tofiledate="(modified)",
+					lineterm='',
+					)
+
+	file_regression.check(
+			diff,
+			encoding="UTF-8",
+			extension=".txt"
+			)