diff --git a/changelog/6566.bugfix.rst b/changelog/6566.bugfix.rst
new file mode 100644
index 000000000..4af976f22
--- /dev/null
+++ b/changelog/6566.bugfix.rst
@@ -0,0 +1 @@
+Fix ``EncodedFile.writelines`` to call the underlying buffer's ``writelines`` method.
diff --git a/scripts/report-coverage.sh b/scripts/report-coverage.sh
index fbcf20ca9..6aa931383 100755
--- a/scripts/report-coverage.sh
+++ b/scripts/report-coverage.sh
@@ -14,5 +14,5 @@ python -m coverage combine
 python -m coverage xml
 python -m coverage report -m
 # Set --connect-timeout to work around https://github.com/curl/curl/issues/4461
-curl -S -L --connect-timeout 5 --retry 6 -s https://codecov.io/bash -o codecov-upload.sh
+curl -S -L --connect-timeout 5 --retry 6 --retry-connrefused -s https://codecov.io/bash -o codecov-upload.sh
 bash codecov-upload.sh -Z -X fix -f coverage.xml "$@"
diff --git a/setup.cfg b/setup.cfg
index 54b64af96..708951da4 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -10,7 +10,6 @@ project_urls =
 author = Holger Krekel, Bruno Oliveira, Ronny Pfannschmidt, Floris Bruynooghe, Brianna Laugher, Florian Bruhin and others
 
 license = MIT license
-license_file = LICENSE
 keywords = test, unittest
 classifiers =
     Development Status :: 6 - Mature
@@ -66,6 +65,7 @@ formats = sdist.tgz,bdist_wheel
 mypy_path = src
 ignore_missing_imports = True
 no_implicit_optional = True
+show_error_codes = True
 strict_equality = True
 warn_redundant_casts = True
 warn_return_any = True
diff --git a/src/_pytest/capture.py b/src/_pytest/capture.py
index 26b473bb0..08f520629 100644
--- a/src/_pytest/capture.py
+++ b/src/_pytest/capture.py
@@ -9,6 +9,8 @@ import os
 import sys
 from io import UnsupportedOperation
 from tempfile import TemporaryFile
+from typing import BinaryIO
+from typing import Iterable
 
 import pytest
 from _pytest.compat import CaptureAndPassthroughIO
@@ -416,30 +418,27 @@ def safe_text_dupfile(f, mode, default_encoding="UTF8"):
 class EncodedFile:
     errors = "strict"  # possibly needed by py3 code (issue555)
 
-    def __init__(self, buffer, encoding):
+    def __init__(self, buffer: BinaryIO, encoding: str) -> None:
         self.buffer = buffer
         self.encoding = encoding
 
-    def write(self, obj):
-        if isinstance(obj, str):
-            obj = obj.encode(self.encoding, "replace")
-        else:
+    def write(self, s: str) -> int:
+        if not isinstance(s, str):
             raise TypeError(
-                "write() argument must be str, not {}".format(type(obj).__name__)
+                "write() argument must be str, not {}".format(type(s).__name__)
             )
-        return self.buffer.write(obj)
+        return self.buffer.write(s.encode(self.encoding, "replace"))
 
-    def writelines(self, linelist):
-        data = "".join(linelist)
-        self.write(data)
+    def writelines(self, lines: Iterable[str]) -> None:
+        self.buffer.writelines(x.encode(self.encoding, "replace") for x in lines)
 
     @property
-    def name(self):
+    def name(self) -> str:
         """Ensure that file.name is a string."""
         return repr(self.buffer)
 
     @property
-    def mode(self):
+    def mode(self) -> str:
         return self.buffer.mode.replace("b", "")
 
     def __getattr__(self, name):
diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index bc62297c1..73c35ce63 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -50,6 +50,13 @@ if TYPE_CHECKING:
     from .argparsing import Argument
 
 
+_PluggyPlugin = object
+"""A type to represent plugin objects.
+Plugins can be any namespace, so we can't narrow it down much, but we use an
+alias to make the intent clear.
+Ideally this type would be provided by pluggy itself."""
+
+
 hookimpl = HookimplMarker("pytest")
 hookspec = HookspecMarker("pytest")
 
diff --git a/src/_pytest/pytester.py b/src/_pytest/pytester.py
index 3f08d5117..5cafa5e7b 100644
--- a/src/_pytest/pytester.py
+++ b/src/_pytest/pytester.py
@@ -29,12 +29,17 @@ from _pytest._io.saferepr import saferepr
 from _pytest.capture import MultiCapture
 from _pytest.capture import SysCapture
 from _pytest.compat import TYPE_CHECKING
+from _pytest.config import _PluggyPlugin
 from _pytest.fixtures import FixtureRequest
 from _pytest.main import ExitCode
 from _pytest.main import Session
 from _pytest.monkeypatch import MonkeyPatch
+from _pytest.nodes import Collector
+from _pytest.nodes import Item
 from _pytest.pathlib import Path
+from _pytest.python import Module
 from _pytest.reports import TestReport
+from _pytest.tmpdir import TempdirFactory
 
 if TYPE_CHECKING:
     from typing import Type
@@ -534,13 +539,15 @@ class Testdir:
     class TimeoutExpired(Exception):
         pass
 
-    def __init__(self, request, tmpdir_factory):
+    def __init__(self, request: FixtureRequest, tmpdir_factory: TempdirFactory) -> None:
         self.request = request
-        self._mod_collections = WeakKeyDictionary()
+        self._mod_collections = (
+            WeakKeyDictionary()
+        )  # type: WeakKeyDictionary[Module, List[Union[Item, Collector]]]
         name = request.function.__name__
         self.tmpdir = tmpdir_factory.mktemp(name, numbered=True)
         self.test_tmproot = tmpdir_factory.mktemp("tmp-" + name, numbered=True)
-        self.plugins = []
+        self.plugins = []  # type: List[Union[str, _PluggyPlugin]]
         self._cwd_snapshot = CwdSnapshot()
         self._sys_path_snapshot = SysPathsSnapshot()
         self._sys_modules_snapshot = self.__take_sys_modules_snapshot()
@@ -1060,7 +1067,9 @@ class Testdir:
         self.config = config = self.parseconfigure(path, *configargs)
         return self.getnode(config, path)
 
-    def collect_by_name(self, modcol, name):
+    def collect_by_name(
+        self, modcol: Module, name: str
+    ) -> Optional[Union[Item, Collector]]:
         """Return the collection node for name from the module collection.
 
         This will search a module collection node for a collection node
@@ -1069,13 +1078,13 @@ class Testdir:
         :param modcol: a module collection node; see :py:meth:`getmodulecol`
 
         :param name: the name of the node to return
-
         """
         if modcol not in self._mod_collections:
             self._mod_collections[modcol] = list(modcol.collect())
         for colitem in self._mod_collections[modcol]:
             if colitem.name == name:
                 return colitem
+        return None
 
     def popen(
         self,
diff --git a/testing/logging/test_reporting.py b/testing/logging/test_reporting.py
index 201f42f32..4333bbb00 100644
--- a/testing/logging/test_reporting.py
+++ b/testing/logging/test_reporting.py
@@ -946,7 +946,7 @@ def test_collection_collect_only_live_logging(testdir, verbose):
         expected_lines.extend(
             [
                 "*test_collection_collect_only_live_logging.py::test_simple*",
-                "no tests ran in 0.[0-9][0-9]s",
+                "no tests ran in [0-1].[0-9][0-9]s",
             ]
         )
     elif verbose == "-qq":
diff --git a/testing/test_capture.py b/testing/test_capture.py
index e0e38ea51..7d6afa1e4 100644
--- a/testing/test_capture.py
+++ b/testing/test_capture.py
@@ -7,6 +7,8 @@ import sys
 import textwrap
 from io import StringIO
 from io import UnsupportedOperation
+from typing import BinaryIO
+from typing import Generator
 from typing import List
 from typing import TextIO
 
@@ -854,7 +856,7 @@ def test_dontreadfrominput():
 
 
 @pytest.fixture
-def tmpfile(testdir):
+def tmpfile(testdir) -> Generator[BinaryIO, None, None]:
     f = testdir.makepyfile("").open("wb+")
     yield f
     if not f.closed:
@@ -1537,3 +1539,15 @@ def test_typeerror_encodedfile_write(testdir):
 def test_stderr_write_returns_len(capsys):
     """Write on Encoded files, namely captured stderr, should return number of characters written."""
     assert sys.stderr.write("Foo") == 3
+
+
+def test_encodedfile_writelines(tmpfile: BinaryIO) -> None:
+    ef = capture.EncodedFile(tmpfile, "utf-8")
+    with pytest.raises(AttributeError):
+        ef.writelines([b"line1", b"line2"])  # type: ignore[list-item]  # noqa: F821
+    assert ef.writelines(["line1", "line2"]) is None  # type: ignore[func-returns-value]  # noqa: F821
+    tmpfile.seek(0)
+    assert tmpfile.read() == b"line1line2"
+    tmpfile.close()
+    with pytest.raises(ValueError):
+        ef.read()
diff --git a/testing/test_collection.py b/testing/test_collection.py
index 760cb2b7f..56f2efc84 100644
--- a/testing/test_collection.py
+++ b/testing/test_collection.py
@@ -9,6 +9,7 @@ import pytest
 from _pytest.main import _in_venv
 from _pytest.main import ExitCode
 from _pytest.main import Session
+from _pytest.pytester import Testdir
 
 
 class TestCollector:
@@ -18,7 +19,7 @@ class TestCollector:
         assert not issubclass(Collector, Item)
         assert not issubclass(Item, Collector)
 
-    def test_check_equality(self, testdir):
+    def test_check_equality(self, testdir: Testdir) -> None:
         modcol = testdir.getmodulecol(
             """
             def test_pass(): pass
@@ -40,12 +41,15 @@ class TestCollector:
         assert fn1 != fn3
 
         for fn in fn1, fn2, fn3:
-            assert fn != 3
+            assert isinstance(fn, pytest.Function)
+            assert fn != 3  # type: ignore[comparison-overlap]  # noqa: F821
             assert fn != modcol
-            assert fn != [1, 2, 3]
-            assert [1, 2, 3] != fn
+            assert fn != [1, 2, 3]  # type: ignore[comparison-overlap]  # noqa: F821
+            assert [1, 2, 3] != fn  # type: ignore[comparison-overlap]  # noqa: F821
             assert modcol != fn
 
+        assert testdir.collect_by_name(modcol, "doesnotexist") is None
+
     def test_getparent(self, testdir):
         modcol = testdir.getmodulecol(
             """
diff --git a/testing/test_config.py b/testing/test_config.py
index 498cbf7eb..cc54e5b23 100644
--- a/testing/test_config.py
+++ b/testing/test_config.py
@@ -670,6 +670,32 @@ def test_disable_plugin_autoload(testdir, monkeypatch, parse_args, should_load):
     assert has_loaded == should_load
 
 
+def test_plugin_loading_order(testdir):
+    """Test order of plugin loading with `-p`."""
+    p1 = testdir.makepyfile(
+        """
+        def test_terminal_plugin(request):
+            import myplugin
+            assert myplugin.terminal_plugin == [True, True]
+        """,
+        **{
+            "myplugin": """
+            terminal_plugin = []
+
+            def pytest_configure(config):
+                terminal_plugin.append(bool(config.pluginmanager.get_plugin("terminalreporter")))
+
+            def pytest_sessionstart(session):
+                config = session.config
+                terminal_plugin.append(bool(config.pluginmanager.get_plugin("terminalreporter")))
+            """
+        }
+    )
+    testdir.syspathinsert()
+    result = testdir.runpytest("-p", "myplugin", str(p1))
+    assert result.ret == 0
+
+
 def test_cmdline_processargs_simple(testdir):
     testdir.makeconftest(
         """
diff --git a/testing/test_terminal.py b/testing/test_terminal.py
index 88ee75493..8c14acc80 100644
--- a/testing/test_terminal.py
+++ b/testing/test_terminal.py
@@ -13,6 +13,7 @@ import py
 
 import pytest
 from _pytest.main import ExitCode
+from _pytest.pytester import Testdir
 from _pytest.reports import BaseReport
 from _pytest.terminal import _folded_skips
 from _pytest.terminal import _get_line_with_reprcrash_message
@@ -1978,3 +1979,11 @@ def test_collecterror(testdir):
             "*= 1 error in *",
         ]
     )
+
+
+def test_via_exec(testdir: Testdir) -> None:
+    p1 = testdir.makepyfile("exec('def test_via_exec(): pass')")
+    result = testdir.runpytest(str(p1), "-vv")
+    result.stdout.fnmatch_lines(
+        ["test_via_exec.py::test_via_exec <- <string> PASSED*", "*= 1 passed in *"]
+    )