Fix the deprecation of set_output in our code (#5209)

* Fix the deprecation of set_output in our code

* Add a test for the deprecation warning itself

* Refactor the set_output from the MultiReporter

We can remove set_output declaration because the function was already failing
with a NotImplementedError before, so removing it make it fail another way

3 files changed, 17 insertions, 16 deletions

diff --git a/pylint/lint/pylinter.py b/pylint/lint/pylinter.py
index ae2126c09..ede27d1e8 100644
--- a/pylint/lint/pylinter.py
+++ b/pylint/lint/pylinter.py
@@ -618,16 +618,13 @@ class PyLinter(
 
                 reporter = self._load_reporter_by_name(reporter_name)
                 sub_reporters.append(reporter)
-
                 if reporter_output:
                     (reporter_output,) = reporter_output
-
                     # pylint: disable=consider-using-with
                     output_file = stack.enter_context(
                         open(reporter_output, "w", encoding="utf-8")
                     )
-
-                    reporter.set_output(output_file)
+                    reporter.out = output_file
                     output_files.append(output_file)
 
             # Extend the lifetime of all opened output files
diff --git a/pylint/lint/run.py b/pylint/lint/run.py
index 4348fd721..22c3dd14f 100644
--- a/pylint/lint/run.py
+++ b/pylint/lint/run.py
@@ -377,7 +377,7 @@ to search for configuration file.
         if self._output:
             try:
                 with open(self._output, "w", encoding="utf-8") as output:
-                    linter.reporter.set_output(output)
+                    linter.reporter.out = output
                     linter.check(args)
                     score_value = linter.generate_reports()
             except OSError as ex:
diff --git a/pylint/reporters/multi_reporter.py b/pylint/reporters/multi_reporter.py
index a6be1c1b8..f674a29e4 100644
--- a/pylint/reporters/multi_reporter.py
+++ b/pylint/reporters/multi_reporter.py
@@ -38,11 +38,24 @@ class MultiReporter:
     ):
         self._sub_reporters = sub_reporters
         self.close_output_files = close_output_files
-
         self._path_strip_prefix = os.getcwd() + os.sep
         self._linter: Optional[PyLinter] = None
+        self.out = output
 
-        self.set_output(output)
+    @property
+    def out(self):
+        return self.__out
+
+    @out.setter
+    def out(self, output: Optional[AnyFile] = None):
+        """
+        MultiReporter doesn't have it's own output. This method is only
+        provided for API parity with BaseReporter and should not be called
+        with non-None values for 'output'.
+        """
+        self.__out = None
+        if output is not None:
+            raise NotImplementedError("MultiReporter does not support direct output.")
 
     def __del__(self) -> None:
         self.close_output_files()
@@ -66,15 +79,6 @@ class MultiReporter:
         for rep in self._sub_reporters:
             rep.handle_message(msg)
 
-    # pylint: disable=no-self-use
-    def set_output(self, output: Optional[AnyFile] = None) -> None:
-        """set output stream"""
-        # MultiReporter doesn't have it's own output. This method is only
-        # provided for API parity with BaseReporter and should not be called
-        # with non-None values for 'output'.
-        if output is not None:
-            raise NotImplementedError("MultiReporter does not support direct output.")
-
     def writeln(self, string: str = "") -> None:
         """write a line in the output buffer"""
         for rep in self._sub_reporters: