Makefile: merge check-flake8 into check-package

Teach check-package to detect python files by type and check them using
flake8.
Do not use subprocess to call 'python3 -m flake8' in order to avoid too
many spawned shells, which in its turn would slow down the check for
multiple files. (make check-package takes twice the time using a shell
for each flake8 call, when compared of importing the main application)

Expand the runtime test and the unit tests for check-package.

Remove check-flake8 from the makefile and also from the GitLab CI
because the exact same checks become part of check-package.

Suggested-by: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
[Arnout: add a comment to x-python to explain its purpose]
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

utils/check-package

@@ -14,6 +14,7 @@ import checkpackagelib.lib_config
 import checkpackagelib.lib_hash
 import checkpackagelib.lib_mk
 import checkpackagelib.lib_patch
+import checkpackagelib.lib_python
 import checkpackagelib.lib_shellscript
 import checkpackagelib.lib_sysv
 
@@ -100,6 +101,8 @@ def get_lib_from_filetype(fname):
     filetype = get_filetype(fname)
     if filetype == "text/x-shellscript":
         return checkpackagelib.lib_shellscript
+    if filetype in ["text/x-python", "text/x-script.python"]:
+        return checkpackagelib.lib_python
     return None
 
 

utils/checkpackagelib/lib_python.py

@@ -0,0 +1 @@
+from checkpackagelib.tool import Flake8                # noqa: F401

utils/checkpackagelib/test_tool.py

@@ -66,6 +66,34 @@ def test_NotExecutable_hint(testname, hint, filename, permissions, string, expec
     assert warnings == expected
 
 
+Flake8 = [
+    ('empty',
+     'empty.py',
+     '',
+     []),
+    ('W391',
+     'blank-line.py',
+     '\n',
+     ["dir/blank-line.py:0: run 'flake8' and fix the warnings",
+      "dir/blank-line.py:1:1: W391 blank line at end of file"]),
+    ('more than one warning',
+     'file',
+     'import os\n'
+     'import re\n'
+     '\n',
+     ["dir/file:0: run 'flake8' and fix the warnings",
+      "dir/file:1:1: F401 'os' imported but unused\n"
+      "dir/file:2:1: F401 're' imported but unused\n"
+      'dir/file:3:1: W391 blank line at end of file']),
+    ]
+
+
+@pytest.mark.parametrize('testname,filename,string,expected', Flake8)
+def test_Flake8(testname, filename, string, expected):
+    warnings = check_file(m.Flake8, filename, string)
+    assert warnings == expected
+
+
 Shellcheck = [
     ('missing shebang',
      'empty.sh',

utils/checkpackagelib/tool.py

@@ -1,5 +1,7 @@
+import flake8.main.application
 import os
 import subprocess
+import tempfile
 from checkpackagelib.base import _Tool
 
 
@@ -14,6 +16,19 @@ class NotExecutable(_Tool):
             return ["{}:0: This file does not need to be executable{}".format(self.filename, self.hint())]
 
 
+class Flake8(_Tool):
+    def run(self):
+        with tempfile.NamedTemporaryFile() as output:
+            app = flake8.main.application.Application()
+            app.run(['--output-file={}'.format(output.name), self.filename])
+            stdout = output.readlines()
+            processed_output = [str(line.decode().rstrip()) for line in stdout if line]
+            if len(stdout) == 0:
+                return
+            return ["{}:0: run 'flake8' and fix the warnings".format(self.filename),
+                    '\n'.join(processed_output)]
+
+
 class Shellcheck(_Tool):
     def run(self):
         cmd = ['shellcheck', self.filename]