Collectors: Create basic bear collector by aspect

Enable coala to collect bears based on aspects configuration.
Currently, the algorithm to collects is very simple, iterate
over all bears in coala and pick the first bear that capable to
handle an aspect and have compatible language. Improvement will
be implemented in future patch.

Closes #4531

coalib/collecting/Collectors.py

@@ -204,6 +204,33 @@ def filter_section_bears_by_languages(bears, languages):
     return new_bears
 
 
+def collect_bears_by_aspects(aspects, kinds):
+    """
+    Collect bear based on aspects.
+
+    Return a list of bears that have capability to analyze all aspects from
+    given AspectList requirement.
+
+    :param aspects: An AspectList that need to be covered.
+    :param kinds:   List of bear kinds to be collected.
+    :return:        Tuple of list of bear classes based on kind. The lists are
+                    in the same order as kinds.
+    """
+    all_bears = get_all_bears()
+    bears_found = tuple([] for i in range(len(kinds)))
+    for aspect in aspects.get_leaf_aspects():
+        for bear in all_bears:
+            if (aspect in bear.aspects['detect'] or
+                    aspect in bear.aspects['fix']):
+                index = kinds.index(_get_kind(bear))
+                # Avoid duplicate
+                if bear not in bears_found[index]:
+                    bears_found[index].append(bear)
+                break
+
+    return bears_found
+
+
 def filter_capabilities_by_languages(bears, languages):
     """
     Filters the bears capabilities by languages.

coalib/settings/ConfigurationGathering.py

@@ -30,8 +30,13 @@ def aspectize_sections(sections):
     :param sections:  List of section that potentially contain aspects setting.
     :return:          The new sections.
     """
-    for _, section in sections.items():
+    for section_name, section in sections.items():
         section.aspects = extract_aspects_from_section(section)
+        if section.aspects is not None and len(section.get('bears')):
+            logging.warning("'aspects' and 'bears' configuration is detected "
+                            "in section '{}'. Aspect-based configuration will "
+                            'takes priority and will overwrite any '
+                            'explicitly listed bears'.format(section_name))
     return sections
 
 

coalib/settings/SectionFilling.py

@@ -2,7 +2,8 @@
 
 from coalib.bears.BEAR_KIND import BEAR_KIND
 from coalib.collecting import Dependencies
-from coalib.collecting.Collectors import collect_bears
+from coalib.collecting.Collectors import (
+    collect_bears, collect_bears_by_aspects)
 from coalib.settings.Setting import Setting
 
 
@@ -83,12 +84,18 @@ def fill_settings(sections,
 
     for section_name, section in sections.items():
         bear_dirs = section.bear_dirs()
-        bears = list(section.get('bears', ''))
-        section_local_bears, section_global_bears = collect_bears(
-            bear_dirs,
-            bears,
-            [BEAR_KIND.LOCAL, BEAR_KIND.GLOBAL],
-            log_printer)
+        if getattr(section, 'aspects', None):
+            section_local_bears, section_global_bears = (
+                collect_bears_by_aspects(
+                    section.aspects,
+                    [BEAR_KIND.LOCAL, BEAR_KIND.GLOBAL]))
+        else:
+            bears = list(section.get('bears', ''))
+            section_local_bears, section_global_bears = collect_bears(
+                bear_dirs,
+                bears,
+                [BEAR_KIND.LOCAL, BEAR_KIND.GLOBAL],
+                log_printer)
         section_local_bears = Dependencies.resolve(section_local_bears)
         section_global_bears = Dependencies.resolve(section_global_bears)
         all_bears = copy.deepcopy(section_local_bears)

tests/collecting/CollectorsTest.py

@@ -4,11 +4,13 @@
 
 from pyprint.ConsolePrinter import ConsolePrinter
 
+from coalib.bearlib.aspects import AspectList, get as get_aspect
+from coalib.bears.BEAR_KIND import BEAR_KIND
 from coalib.bears.Bear import Bear
 from coalib.collecting.Collectors import (
     collect_all_bears_from_sections, collect_bears, collect_dirs, collect_files,
     collect_registered_bears_dirs, filter_section_bears_by_languages,
-    get_all_bears, get_all_bears_names)
+    get_all_bears, get_all_bears_names, collect_bears_by_aspects)
 from coalib.output.printers.LogPrinter import LogPrinter
 from coalib.output.printers.ListLogPrinter import ListLogPrinter
 from coalib.settings.Section import Section
@@ -275,6 +277,17 @@ def test_all_bears_from_sections(self):
         self.assertEqual(len(local_bears['test_section']), 2)
         self.assertEqual(len(global_bears['test_section']), 2)
 
+    def test_aspect_bear(self):
+        with bear_test_module():
+            aspects = AspectList([get_aspect('unusedvariable')('py')])
+            local_bears, global_bears = collect_bears_by_aspects(
+                aspects,
+                [BEAR_KIND.LOCAL, BEAR_KIND.GLOBAL])
+
+        self.assertEqual(len(global_bears), 0)
+        self.assertEqual(len(local_bears), 1)
+        self.assertIs(local_bears[0].name, 'AspectTestBear')
+
 
 class CollectorsTests(unittest.TestCase):