Add function 'select_license_by_source' and use it

piplicenses.py

@@ -165,9 +165,16 @@ def get_pkg_info(pkg):
         for key in METADATA_KEYS:
             pkg_info[key] = parsed_metadata.get(key, LICENSE_UNKNOWN)
 
-        if getattr(args, 'from') == 'classifier' and metadata is not None:
+        from_source = getattr(args, 'from')
+        need_classifier = from_source == 'classifier' or from_source == 'mixed'
+        if need_classifier and metadata is not None:
             message = message_from_string(metadata)
-            pkg_info['license'] = find_license_from_classifier(message)
+            license_classifier = find_license_from_classifier(message)
+            license_meta = pkg_info['license']
+            # Overwrite license by condition
+            pkg_info['license'] = select_license_by_source(from_source,
+                                                           license_classifier,
+                                                           license_meta)
 
         return pkg_info
 
@@ -287,6 +294,16 @@ def find_license_from_classifier(message):
     return license_from_classifier
 
 
+def select_license_by_source(from_source, license_classifier, license_meta):
+    if from_source == 'classifier':
+        return license_classifier
+    elif from_source == 'mixed':
+        if license_classifier != LICENSE_UNKNOWN:
+            return license_classifier
+        else:
+            return license_meta
+
+
 def get_output_fields(args):
     if args.summary:
         return list(SUMMARY_OUTPUT_FIELDS)
@@ -391,6 +408,9 @@ def _compatible_format_args(self, args):
         if from_input in ('classifier', 'c'):
             setattr(args, 'from', 'classifier')
 
+        if from_input in ('mixed', 'mix'):
+            setattr(args, 'from', 'mixed')
+
         if order_input in ('count', 'c'):
             args.order = 'count'
 
@@ -449,7 +469,7 @@ def create_parser():
                         action='store', type=str,
                         default='meta', metavar='SOURCE',
                         help=('where to find license information\n'
-                              '"meta", "classifier"\n'
+                              '"meta", "classifier, "mixed"\n'
                               'default: --from=meta'))
     parser.add_argument('-c', '--from-classifier',
                         action='store_true',

test_piplicenses.py

@@ -9,6 +9,7 @@
                          create_licenses_table, get_output_fields, get_sortby,
                          factory_styled_table_with_args, create_warn_string,
                          find_license_from_classifier, create_output_string,
+                         select_license_by_source,
                          DEFAULT_OUTPUT_FIELDS, SYSTEM_PACKAGES,
                          LICENSE_UNKNOWN)
 
@@ -85,6 +86,19 @@ def test_from_classifier(self):
         license_notation_as_classifier = 'MIT License'
         self.assertIn(license_notation_as_classifier, license_columns)
 
+    def test_from_mixed(self):
+        from_classifier_args = ['--from=mixed']
+        args = self.parser.parse_args(from_classifier_args)
+        table = create_licenses_table(args)
+
+        output_fields = get_output_fields(args)
+        self.assertIn('License', output_fields)
+
+        license_columns = self._create_license_columns(table)
+        # Depending on the condition "MIT" or "BSD" etc.
+        license_notation_as_classifier = 'MIT License'
+        self.assertIn(license_notation_as_classifier, license_columns)
+
     def test_find_license_from_classifier(self):
         metadata = ('Metadata-Version: 2.0\r\n'
                     'Name: pip-licenses\r\n'
@@ -117,6 +131,27 @@ def test_not_found_license_from_classifier(self):
         self.assertEqual(LICENSE_UNKNOWN,
                          find_license_from_classifier(message))
 
+    def test_select_license_by_source(self):
+        self.assertEqual('MIT License',
+                         select_license_by_source('classifier',
+                                                  'MIT License',
+                                                  'MIT'))
+
+        self.assertEqual(LICENSE_UNKNOWN,
+                         select_license_by_source('classifier',
+                                                  LICENSE_UNKNOWN,
+                                                  'MIT'))
+
+        self.assertEqual('MIT License',
+                         select_license_by_source('mixed',
+                                                  'MIT License',
+                                                  'MIT'))
+
+        self.assertEqual('MIT',
+                         select_license_by_source('mixed',
+                                                  LICENSE_UNKNOWN,
+                                                  'MIT'))
+
     def test_with_system(self):
         with_system_args = ['--with-system']
         args = self.parser.parse_args(with_system_args)