Add typing to ``PyLinter.reporter`` (#5325)

* Add ``messages`` attribute to ``MultiReporter``

* Make ``PyLinter`` always have a ``reporter`` attribute

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

6 files changed, 34 insertions, 11 deletions

diff --git a/ChangeLog b/ChangeLog
index 02cd4eea7..f946dbbc5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -27,6 +27,9 @@ Release date: TBA
   Insert your changelog randomly, it will reduce merge conflicts
   (Ie. not necessarily at the end)
 
+* The ``PyLinter`` class will now be initialiazed with a ``TextReporter``
+  as its reporter if none is provided.
+
 
 What's New in Pylint 2.12.2?
 ============================
diff --git a/doc/whatsnew/2.13.rst b/doc/whatsnew/2.13.rst
index 8222813d2..0713e343a 100644
--- a/doc/whatsnew/2.13.rst
+++ b/doc/whatsnew/2.13.rst
@@ -34,3 +34,6 @@ Other Changes
 * Require Python ``3.6.2`` to run pylint.
 
   Closes #5065
+
+* The ``PyLinter`` class will now be initialiazed with a ``TextReporter``
+  as its reporter if none is provided.
diff --git a/pylint/lint/pylinter.py b/pylint/lint/pylinter.py
index c95aa680e..3617d9141 100644
--- a/pylint/lint/pylinter.py
+++ b/pylint/lint/pylinter.py
@@ -39,6 +39,7 @@ from pylint.lint.utils import (
     prepare_crash_report,
 )
 from pylint.message import Message, MessageDefinition, MessageDefinitionStore
+from pylint.reporters.text import TextReporter
 from pylint.reporters.ureports import nodes as report_nodes
 from pylint.typing import (
     FileItem,
@@ -517,13 +518,25 @@ class PyLinter(
         ("Reports", "Options related to output formatting and reporting"),
     )
 
-    def __init__(self, options=(), reporter=None, option_groups=(), pylintrc=None):
+    def __init__(
+        self,
+        options=(),
+        reporter=None,
+        option_groups=(),
+        pylintrc=None,
+    ):
         """Some stuff has to be done before ancestors initialization...
         messages store / checkers / reporter / astroid manager"""
-        self.msgs_store = MessageDefinitionStore()
-        self.reporter = None
+        # Attributes for reporters
+        self.reporter: Union[reporters.BaseReporter, reporters.MultiReporter]
+        if reporter:
+            self.set_reporter(reporter)
+        else:
+            self.set_reporter(TextReporter())
         self._reporter_names = None
         self._reporters = {}
+
+        self.msgs_store = MessageDefinitionStore()
         self._checkers = collections.defaultdict(list)
         self._pragma_lineno = {}
         self._ignore_file = False
@@ -572,16 +585,10 @@ class PyLinter(
         self._dynamic_plugins = set()
         self._error_mode = False
         self.load_provider_defaults()
-        if reporter:
-            self.set_reporter(reporter)
 
     def load_default_plugins(self):
         checkers.initialize(self)
         reporters.initialize(self)
-        # Make sure to load the default reporter, because
-        # the option has been set before the plugins had been loaded.
-        if not self.reporter:
-            self._load_reporters()
 
     def load_plugin_modules(self, modnames):
         """take a list of module names which are pylint plugins and load
@@ -654,7 +661,9 @@ class PyLinter(
         else:
             return reporter_class()
 
-    def set_reporter(self, reporter):
+    def set_reporter(
+        self, reporter: Union[reporters.BaseReporter, reporters.MultiReporter]
+    ) -> None:
         """set the reporter used to display messages and reports"""
         self.reporter = reporter
         reporter.linter = self
diff --git a/pylint/reporters/multi_reporter.py b/pylint/reporters/multi_reporter.py
index f674a29e4..cbdc36962 100644
--- a/pylint/reporters/multi_reporter.py
+++ b/pylint/reporters/multi_reporter.py
@@ -41,6 +41,7 @@ class MultiReporter:
         self._path_strip_prefix = os.getcwd() + os.sep
         self._linter: Optional[PyLinter] = None
         self.out = output
+        self.messages: List[Message] = []
 
     @property
     def out(self):
diff --git a/tests/test_self.py b/tests/test_self.py
index 41bf423ec..ebdb91443 100644
--- a/tests/test_self.py
+++ b/tests/test_self.py
@@ -1261,6 +1261,13 @@ class TestRunTC:
         assert sorted(plugins) == sorted(runner.linter._dynamic_plugins)
 
     @staticmethod
+    def test_load_text_repoter_if_not_provided() -> None:
+        """Test if PyLinter.reporter is a TextReporter if no reporter is provided"""
+        linter = PyLinter()
+
+        assert isinstance(linter.reporter, TextReporter)
+
+    @staticmethod
     def test_regex_paths_csv_validator() -> None:
         """Test to see if _regexp_paths_csv_validator works.
         Previously the validator crashed when encountering already validated values.
diff --git a/tests/unittest_reporting.py b/tests/unittest_reporting.py
index 08bd2a345..757987359 100644
--- a/tests/unittest_reporting.py
+++ b/tests/unittest_reporting.py
@@ -190,11 +190,11 @@ def test_multi_format_output(tmp_path):
 
     with redirect_stdout(text):
         linter = PyLinter()
+        linter.load_default_plugins()
         linter.set_option("persistent", False)
         linter.set_option("output-format", formats)
         linter.set_option("reports", True)
         linter.set_option("score", True)
-        linter.load_default_plugins()
 
         assert linter.reporter.linter is linter
         with pytest.raises(NotImplementedError):