add non-default context line unit test

Author: chrissimpkins

tests/test_diff.py

@@ -8,6 +8,7 @@
 ROBOTO_AFTER_PATH = os.path.join("tests", "testfiles", "Roboto-Regular.subset2.ttf")
 ROBOTO_UDIFF_EXPECTED_PATH = os.path.join("tests", "testfiles", "roboto_udiff_expected.txt")
 ROBOTO_UDIFF_COLOR_EXPECTED_PATH = os.path.join("tests", "testfiles", "roboto_udiff_color_expected.txt")
+ROBOTO_UDIFF_1CONTEXT_EXPECTED_PATH = os.path.join("tests", "testfiles", "roboto_udiff_1context_expected.txt")
 
 # Setup: define the expected diff text for unified diff
 with open(ROBOTO_UDIFF_EXPECTED_PATH, "r") as robo_udiff:
@@ -17,6 +18,10 @@
 with open(ROBOTO_UDIFF_COLOR_EXPECTED_PATH, "r") as robo_udiff_color:
     ROBOTO_UDIFF_COLOR_EXPECTED = robo_udiff_color.read()
 
+# Setup: define the expected diff text for unified color diff
+with open(ROBOTO_UDIFF_1CONTEXT_EXPECTED_PATH, "r") as robo_udiff_contextlines:
+    ROBOTO_UDIFF_1CONTEXT_EXPECTED = robo_udiff_contextlines.read()
+
 
 def test_unified_diff_default():
     res = u_diff(ROBOTO_BEFORE_PATH, ROBOTO_AFTER_PATH)
@@ -37,5 +42,24 @@ def test_unified_diff_default():
             assert line == expected_string_list[x]
 
 
+def test_unified_diff_context_lines_1():
+    res = u_diff(ROBOTO_BEFORE_PATH, ROBOTO_AFTER_PATH, context_lines=1)
+    res_string = "".join(res)
+    res_string_list = res_string.split("\n")
+    expected_string_list = ROBOTO_UDIFF_1CONTEXT_EXPECTED.split("\n")
+
+    # have to handle the tests for the top two file path lines
+    # differently than the rest of the comparisons because
+    # the time is defined using local platform settings
+    # which makes tests fail on remote CI testing services vs.
+    # my local testing platform...
+    for x, line in enumerate(res_string_list):
+        # treat top two lines of the diff as comparison of first 10 chars only
+        if x in (0, 1):
+            assert line[0:9] == expected_string_list[x][0:9]
+        else:
+            assert line == expected_string_list[x]
+
+