fix #25 use context mode for long diffs

Author: hjwp

pytest_icdiff.py

@@ -52,6 +52,8 @@ def pytest_assertrepr_compare(config, op, left, right):
     else:
         color_off = icdiff.color_codes['none']
 
-    icdiff_lines = list(differ.make_table(pretty_left, pretty_right, context=True))
+    icdiff_lines = list(differ.make_table(pretty_left, pretty_right))
+    if len(icdiff_lines) > 50:
+        icdiff_lines = list(differ.make_table(pretty_left, pretty_right, context=True)) 
 
     return ['equals failed'] + [color_off + l for l in icdiff_lines]

setup.py

@@ -13,7 +13,7 @@ def read(fname):
 
 setup(
     name='pytest-icdiff',
-    version='0.5',
+    version='0.6',
     author='Harry Percival',
     author_email='[email protected]',
     maintainer='Harry Percival',

tests/test_pytest_icdiff.py

@@ -275,3 +275,17 @@ def test_one():
     )
     output = testdir.runpytest('-vv', '--color=yes').stdout.str()
     assert f"123456   123456{GREEN_ON}7" in output
+
+
+def test_really_long_diffs_use_context_mode(testdir):
+    testdir.makepyfile(
+        f"""
+        def test_one():
+            one = list(range(100))
+            two = list(range(20)) + ["X"] + list(range(20, 50)) + ["Y"] + list(range(53, 100))
+            assert one == two
+        """
+    )
+    output = testdir.runpytest('-vv', '--color=yes').stdout.str()
+    assert len(output.splitlines()) < 50
+    assert "---" in output  # context split marker