.coafile: Activate remove_all_unused_imports

Adds flakes section to check non-builtin unused imports.
Automatic fixes may remove critical imports.
Adds ignore comment to non-builtin imports as required.
Removes unused import where necessary.

Closes coala#1600

.coafile

@@ -15,6 +15,14 @@ language = python
 default_actions = *: ApplyPatchAction
 preferred_quotation = '
 
+[flakes]
+# Do not set default_action to ApplyPatchAction as it may lead to some
+# required imports being removed which might result in coala behaving weirdly.
+default_action: *: ShowPatchAction
+bears = PyUnusedCodeBear
+language = Python
+remove_all_unused_imports = true
+
 [autopep8]
 bears = PEP8Bear, PycodestyleBear
 default_actions = PEP8Bear: ApplyPatchAction

bears/Constants.py

@@ -1,6 +1,8 @@
 import os
 
+# Start ignoring PyUnusedCodeBear
 from bears import VERSION
+# Stop ignoring PyUnusedCodeBear
 
 # Path to the bears directory
 bears_root = os.path.dirname(__file__)

bears/c_languages/ClangBear.py

@@ -1,7 +1,6 @@
 from clang.cindex import Index, LibclangError
 
 from coalib.bears.LocalBear import LocalBear
-from dependency_management.requirements.PipRequirement import PipRequirement
 from coalib.results.Diff import Diff
 from coalib.results.Result import Result
 from coalib.results.RESULT_SEVERITY import RESULT_SEVERITY

bears/css/StyleLintBear.py

@@ -1,4 +1,3 @@
-import os
 import json
 from coalib.bearlib.abstractions.Linter import linter
 from dependency_management.requirements.NpmRequirement import NpmRequirement

bears/perl/PerlCriticBear.py

@@ -1,5 +1,3 @@
-import platform
-
 from coalib.bearlib.abstractions.Linter import linter
 from dependency_management.requirements.DistributionRequirement import (
     DistributionRequirement)

bears/ruby/RubySyntaxBear.py

@@ -1,5 +1,4 @@
 from coalib.bearlib.abstractions.Linter import linter
-from dependency_management.requirements.GemRequirement import GemRequirement
 from dependency_management.requirements.DistributionRequirement import (
     DistributionRequirement)
 

tests/css/StyleLintBearTest.py

@@ -1,13 +1,11 @@
 import os
-import re
 from queue import Queue
 from shutil import which
 from unittest.case import skipIf
 
 from bears.css.StyleLintBear import StyleLintBear
 from coalib.testing.LocalBearTestHelper import LocalBearTestHelper
 from coalib.settings.Section import Section
-from coalib.settings.Setting import Setting
 
 
 @skipIf(which('stylelint') is None, 'Stylelint is not installed')

tests/haskell/GhcModBearTest.py

@@ -2,10 +2,8 @@
 
 from bears.haskell.GhcModBear import GhcModBear
 from coalib.testing.LocalBearTestHelper import LocalBearTestHelper
-from coalib.testing.LocalBearTestHelper import verify_local_bear
 from coalib.testing.BearTestHelper import generate_skip_decorator
 from coalib.settings.Section import Section
-from coalib.settings.Setting import Setting
 
 
 # A simple hello world program!

tests/haskell/HaskellLintBearTest.py

@@ -2,10 +2,9 @@
 
 from bears.haskell.HaskellLintBear import HaskellLintBear
 from coalib.testing.LocalBearTestHelper import LocalBearTestHelper
-from coalib.testing.LocalBearTestHelper import verify_local_bear
 from coalib.testing.BearTestHelper import generate_skip_decorator
 from coalib.settings.Section import Section
-from coalib.settings.Setting import Setting
+
 
 good_single_line_file = """
 myconcat = (++)