Use diff_cover.

.travis.yml

@@ -30,6 +30,10 @@ matrix:
     # on starting separate jobs.
     - python: 2.7
       env: TOXENV=narrativedocs,apidocs,pyflakes,topfile,manifest-checker
+    # Twistedchecker is running as a separate job so that we can ignore if it
+    # fails.
+    - python: 2.7
+      env: TOXENV=txchecker-travis
     #
     # OSX 10.10
     #
@@ -44,6 +48,9 @@ matrix:
   allow_failures:
     # For now, OSX run on Travis-CI has a few failures.
     - os: osx
+    # twistedchecker job was introduce as an experimental job.
+    # Once it is stable we can enforce it
+    - env: TOXENV=txchecker-travis
 
 
 addons:

.travis/twistedchecker-trunk-diff.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env sh
+#
+# Helper for running twistedchecker and reporting only errors that are part
+# of the changes since trunk.
+#
+# Call it as:
+# * SCRIPT_NAME twisted
+# * SCRIPT_NAME twisted/words/
+# * SCRIPT_NAME twisted.words
+
+target=$1
+
+# FIXME: https://github.com/twisted/twistedchecker/issues/116
+# Since for unknown modules twistedchecker will return the same error, the
+# diff will fail to detect that we are trying to check an invalid path or
+# module.
+# This is why we check that the argument is a path and if not a path, it is
+# an importable module.
+if [ ! -d "$target" ]; then
+    python -c "import $target" 2> /dev/null
+    if [ $? -ne 0 ]; then
+        >&2 echo "$target does not exists as a path or as a module."
+        exit 1
+    fi
+fi
+
+# Make sure we have trunk on the local repo.
+git fetch origin trunk:refs/remotes/origin/trunk
+
+mkdir -p build/
+twistedchecker -f parseable $target > build/twistedchecker-branch.report
+
+# Make sure repo is producing the diff with prefix so that the output of
+# `git diff` can be parsed by diff_cover.
+git config diff.noprefix false
+
+diff-quality \
+    --violations=pylint \
+    --fail-under=100 \
+    --compare-branch=origin/trunk build/twistedchecker-branch.report
+
+diff_exit_code=$?
+exit $diff_exit_code

tox.ini

@@ -4,6 +4,9 @@
 ; coverage results to codecov.io. It should be called after running the
 ; standard coverage environment.
 ;
+; A non-default `txchecker-travis` environment is used to run twistedchecker
+; on travis in --diff mode
+;
 [tox]
 skip_missing_interpreters=True
 toxworkdir=build/
@@ -40,8 +43,9 @@ deps =
 
      ; Code quality checkers
      pyflakes: pyflakes
-     twistedchecker: twistedchecker
      manifest-checker: check-manifest
+     {twistedchecker,txchecker}: twistedchecker>=0.6.0
+     txchecker: diff_cover
 
      ; Documentation
      apidocs: pydoctor
@@ -87,6 +91,10 @@ commands =
     codecov-publish: codecov {env:CODECOV_OPTIONS:}
 
     twistedchecker: twistedchecker {posargs:twisted}
+
+    # Run twistedchecker with a diff base on trunk.
+    txchecker-travis: {toxinidir}/.travis/twistedchecker-trunk-diff.sh {posargs:twisted}
+
     pyflakes: pyflakes {posargs:twisted admin bin}
 
     apidocs: {toxinidir}/bin/admin/build-apidocs {toxinidir} apidocs