invoke: add 'lint' task

.travis.yml

@@ -22,4 +22,5 @@ install:
   - pip install -r requirements-dev.txt
 
 script:
+  - invoke lint --with-report
   - invoke test

CONTRIBUTING.rst

@@ -40,7 +40,7 @@ Here are some common project tasks::
 
     pytest          # Run unit tests
     inv docs -o     # Build documentation and show in browser
-    paver lint -m   # Check code quality
+    inv lint        # Check code quality
     inv cov         # Run unit tests & show coverage report
     tox             # Run unit tests in various test environments (multiple Python versions)
 

tasks.py

@@ -5,10 +5,13 @@
 from __future__ import print_function, unicode_literals
 
 import os
+import sys
 import time
 import shutil
+import contextlib
 import subprocess
 import webbrowser
+
 try:
     from pathlib import Path
 except ImportError:
@@ -22,6 +25,17 @@
 SPHINX_AUTOBUILD_PORT = int(os.environ.get('SPHINX_AUTOBUILD_PORT', '8340'))
 
 
+@contextlib.contextmanager
+def pushd(folder):
+    """Context manager to temporarily change directory."""
+    cwd = os.getcwd()
+    try:
+        os.chdir(folder)
+        yield folder
+    finally:
+        os.chdir(cwd)
+
+
 @task
 def test(ctx):
     """Run unit tests."""
@@ -30,14 +44,79 @@ def test(ctx):
 
 @task
 def cov(ctx):
-    """Run unit tests & show coverage report"""
+    """Run unit tests & show coverage report."""
     coverage_index = Path("build/coverage/index.html")
     coverage_index.unlink()
     ctx.run(PYTEST_CMD)
     coverage_index.exists() and webbrowser.open(
         'file://{}'.format(os.path.abspath(coverage_index)))
 
 
+@task(help={
+    'output': 'Create report file (.html, .log, or .txt) [stdout]',
+    'rcfile': 'Configuration file [./pylint.cfg]',
+    'with-report': 'Include summary report',
+})
+def lint(ctx, output='', rcfile='', with_report=False):
+    """Report pylint results."""
+    # report according to file extension
+    report_formats = {
+        ".html": "html",
+        ".log": "parseable",
+        ".txt": "text",
+    }
+
+    lint_build_dir = Path("build/lint")
+    lint_build_dir.exists() or lint_build_dir.makedirs()  # pylint: disable=expression-not-assigned
+
+    argv = []
+    if not rcfile and Path("pylint.cfg").exists():
+        rcfile = "pylint.cfg"
+    if rcfile:
+        argv += ["--rcfile", os.path.abspath(rcfile)]
+    if not with_report:
+        argv += ["-rn"]
+    argv += [
+        "--import-graph", str((lint_build_dir / "imports.dot").resolve()),
+    ]
+    argv += [PROJECT_NAME]
+
+    sys.stderr.write("Running %s::pylint '%s'\n" % (sys.argv[0], "' '".join(argv)))
+    outfile = output
+    if outfile:
+        outfile = os.path.abspath(outfile)
+
+    try:
+        with pushd("src" if Path("src").exists() else "."):
+            if outfile:
+                argv.extend(["-f", report_formats.get(Path(outfile).ext, "text")])
+                sys.stderr.write("Writing output to %r\n" % (str(outfile),))
+                with open(outfile, "w", encoding='utf-8') as outhandle:
+                    subprocess.check_call(["pylint"] + argv, stdout=outhandle)
+            else:
+                subprocess.check_call(["pylint"] + argv, )
+        sys.stderr.write("invoke::lint - No problems found.\n")
+    except subprocess.CalledProcessError as exc:
+        if exc.returncode & 32:
+            # usage error (internal error in this code)
+            sys.stderr.write("invoke::lint - Usage error, bad arguments %r?!\n" % (argv,))
+            sys.exit(exc.returncode)
+        else:
+            bits = {
+                1: "fatal",
+                2: "error",
+                4: "warning",
+                8: "refactor",
+                16: "convention",
+            }
+            sys.stderr.write("invoke::lint - Some %s message(s) issued.\n" % (
+                ", ".join([text for bit, text in bits.items() if exc.returncode & bit])
+            ))
+            if exc.returncode & 3:
+                sys.stderr.write("invoke::lint - Exiting due to fatal / error message.\n")
+                sys.exit(exc.returncode)
+
+
 def watchdog_pid(ctx):
     """Get watchdog PID via ``netstat``."""
     result = ctx.run('netstat -tulpn 2>/dev/null | grep 127.0.0.1:{:d}'
@@ -49,7 +128,9 @@ def watchdog_pid(ctx):
     return pid
 
 
-@task(help={'open-tab': "Open docs in new browser tab after initial build"})
+@task(help={
+    'open-tab': "Open docs in new browser tab after initial build"
+})
 def docs(ctx, open_tab=False):
     """Start watchdog to build the Sphinx docs."""
     build_dir = 'docs/_build'
@@ -86,7 +167,7 @@ def docs(ctx, open_tab=False):
 
 @task
 def stop(ctx):
-    "Stop Sphinx watchdog"
+    "Stop Sphinx watchdog."
     print("\n*** Stopping watchdog ***\n")
     for i in range(4):
         pid = watchdog_pid(ctx)