kunit: test: Improve error messages for kunit_tool when kunitconfig is invalid

Previous error message for invalid kunitconfig was vague. Added to it so
that it lists invalid fields and prompts for them to be removed.  Added
validate_config function returning whether or not this kconfig is valid.

Signed-off-by: Heidi Fahim <heidifahim@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Author: Heidifahim

tools/testing/kunit/kunit_kernel.py

@@ -93,6 +93,20 @@ def clean(self):
 			return False
 		return True
 
+	def validate_config(self, build_dir):
+		kconfig_path = get_kconfig_path(build_dir)
+		validated_kconfig = kunit_config.Kconfig()
+		validated_kconfig.read_from_file(kconfig_path)
+		if not self._kconfig.is_subset_of(validated_kconfig):
+			invalid = self._kconfig.entries() - validated_kconfig.entries()
+			message = 'Provided Kconfig is not contained in validated .config. Following fields found in kunitconfig, ' \
+					  'but not in .config: %s' % (
+					', '.join([str(e) for e in invalid])
+			)
+			logging.error(message)
+			return False
+		return True
+
 	def build_config(self, build_dir):
 		kconfig_path = get_kconfig_path(build_dir)
 		if build_dir and not os.path.exists(build_dir):
@@ -103,12 +117,7 @@ def build_config(self, build_dir):
 		except ConfigError as e:
 			logging.error(e)
 			return False
-		validated_kconfig = kunit_config.Kconfig()
-		validated_kconfig.read_from_file(kconfig_path)
-		if not self._kconfig.is_subset_of(validated_kconfig):
-			logging.error('Provided Kconfig is not contained in validated .config!')
-			return False
-		return True
+		return self.validate_config(build_dir)
 
 	def build_reconfig(self, build_dir):
 		"""Creates a new .config if it is not a subset of the .kunitconfig."""
@@ -133,12 +142,7 @@ def build_um_kernel(self, jobs, build_dir):
 		except (ConfigError, BuildError) as e:
 			logging.error(e)
 			return False
-		used_kconfig = kunit_config.Kconfig()
-		used_kconfig.read_from_file(get_kconfig_path(build_dir))
-		if not self._kconfig.is_subset_of(used_kconfig):
-			logging.error('Provided Kconfig is not contained in final config!')
-			return False
-		return True
+		return self.validate_config(build_dir)
 
 	def run_kernel(self, args=[], timeout=None, build_dir=''):
 		args.extend(['mem=256M'])