diff --git a/changelog/1403.bugfix.rst b/changelog/1403.bugfix.rst
new file mode 100644
index 000000000..3fb748aec
--- /dev/null
+++ b/changelog/1403.bugfix.rst
@@ -0,0 +1 @@
+Switch from ``imp`` to ``importlib``.
diff --git a/changelog/2761.bugfix.rst b/changelog/2761.bugfix.rst
new file mode 100644
index 000000000..c63f02ecd
--- /dev/null
+++ b/changelog/2761.bugfix.rst
@@ -0,0 +1 @@
+Honor PEP 235 on case-insensitive file systems.
diff --git a/changelog/5078.bugfix.rst b/changelog/5078.bugfix.rst
new file mode 100644
index 000000000..8fed85f5d
--- /dev/null
+++ b/changelog/5078.bugfix.rst
@@ -0,0 +1 @@
+Test module is no longer double-imported when using ``--pyargs``.
diff --git a/changelog/5432.bugfix.rst b/changelog/5432.bugfix.rst
new file mode 100644
index 000000000..44c01c0cf
--- /dev/null
+++ b/changelog/5432.bugfix.rst
@@ -0,0 +1 @@
+Prevent "already imported" warnings from assertion rewriter when invoking pytest in-process multiple times.
diff --git a/changelog/5433.bugfix.rst b/changelog/5433.bugfix.rst
new file mode 100644
index 000000000..c3a7472bc
--- /dev/null
+++ b/changelog/5433.bugfix.rst
@@ -0,0 +1 @@
+Fix assertion rewriting in packages (``__init__.py``).
diff --git a/src/_pytest/assertion/rewrite.py b/src/_pytest/assertion/rewrite.py
index ce698f368..cce980005 100644
--- a/src/_pytest/assertion/rewrite.py
+++ b/src/_pytest/assertion/rewrite.py
@@ -1,18 +1,16 @@
 """Rewrite assertion AST to produce nice error messages"""
 import ast
 import errno
-import imp
+import importlib.machinery
+import importlib.util
 import itertools
 import marshal
 import os
-import re
 import struct
 import sys
 import types
-from importlib.util import spec_from_file_location
 
 import atomicwrites
-import py
 
 from _pytest._io.saferepr import saferepr
 from _pytest.assertion import util
@@ -23,23 +21,13 @@ from _pytest.pathlib import fnmatch_ex
 from _pytest.pathlib import PurePath
 
 # pytest caches rewritten pycs in __pycache__.
-if hasattr(imp, "get_tag"):
-    PYTEST_TAG = imp.get_tag() + "-PYTEST"
-else:
-    if hasattr(sys, "pypy_version_info"):
-        impl = "pypy"
-    else:
-        impl = "cpython"
-    ver = sys.version_info
-    PYTEST_TAG = "{}-{}{}-PYTEST".format(impl, ver[0], ver[1])
-    del ver, impl
-
+PYTEST_TAG = "{}-PYTEST".format(sys.implementation.cache_tag)
 PYC_EXT = ".py" + (__debug__ and "c" or "o")
 PYC_TAIL = "." + PYTEST_TAG + PYC_EXT
 
 
 class AssertionRewritingHook:
-    """PEP302 Import hook which rewrites asserts."""
+    """PEP302/PEP451 import hook which rewrites asserts."""
 
     def __init__(self, config):
         self.config = config
@@ -48,7 +36,6 @@ class AssertionRewritingHook:
         except ValueError:
             self.fnpats = ["test_*.py", "*_test.py"]
         self.session = None
-        self.modules = {}
         self._rewritten_names = set()
         self._must_rewrite = set()
         # flag to guard against trying to rewrite a pyc file while we are already writing another pyc file,
@@ -62,55 +49,51 @@ class AssertionRewritingHook:
         self.session = session
         self._session_paths_checked = False
 
-    def _imp_find_module(self, name, path=None):
-        """Indirection so we can mock calls to find_module originated from the hook during testing"""
-        return imp.find_module(name, path)
+    # Indirection so we can mock calls to find_spec originated from the hook during testing
+    _find_spec = importlib.machinery.PathFinder.find_spec
 
-    def find_module(self, name, path=None):
+    def find_spec(self, name, path=None, target=None):
         if self._writing_pyc:
             return None
         state = self.config._assertstate
         if self._early_rewrite_bailout(name, state):
             return None
         state.trace("find_module called for: %s" % name)
-        names = name.rsplit(".", 1)
-        lastname = names[-1]
-        pth = None
-        if path is not None:
-            # Starting with Python 3.3, path is a _NamespacePath(), which
-            # causes problems if not converted to list.
-            path = list(path)
-            if len(path) == 1:
-                pth = path[0]
-        if pth is None:
-            try:
-                fd, fn, desc = self._imp_find_module(lastname, path)
-            except ImportError:
-                return None
-            if fd is not None:
-                fd.close()
-            tp = desc[2]
-            if tp == imp.PY_COMPILED:
-                if hasattr(imp, "source_from_cache"):
-                    try:
-                        fn = imp.source_from_cache(fn)
-                    except ValueError:
-                        # Python 3 doesn't like orphaned but still-importable
-                        # .pyc files.
-                        fn = fn[:-1]
-                else:
-                    fn = fn[:-1]
-            elif tp != imp.PY_SOURCE:
-                # Don't know what this is.
-                return None
-        else:
-            fn = os.path.join(pth, name.rpartition(".")[2] + ".py")
 
-        fn_pypath = py.path.local(fn)
-        if not self._should_rewrite(name, fn_pypath, state):
+        spec = self._find_spec(name, path)
+        if (
+            # the import machinery could not find a file to import
+            spec is None
+            # this is a namespace package (without `__init__.py`)
+            # there's nothing to rewrite there
+            # python3.5 - python3.6: `namespace`
+            # python3.7+: `None`
+            or spec.origin in {None, "namespace"}
+            # if the file doesn't exist, we can't rewrite it
+            or not os.path.exists(spec.origin)
+        ):
+            return None
+        else:
+            fn = spec.origin
+
+        if not self._should_rewrite(name, fn, state):
             return None
 
-        self._rewritten_names.add(name)
+        return importlib.util.spec_from_file_location(
+            name,
+            fn,
+            loader=self,
+            submodule_search_locations=spec.submodule_search_locations,
+        )
+
+    def create_module(self, spec):
+        return None  # default behaviour is fine
+
+    def exec_module(self, module):
+        fn = module.__spec__.origin
+        state = self.config._assertstate
+
+        self._rewritten_names.add(module.__name__)
 
         # The requested module looks like a test file, so rewrite it. This is
         # the most magical part of the process: load the source, rewrite the
@@ -121,7 +104,7 @@ class AssertionRewritingHook:
         # cached pyc is always a complete, valid pyc. Operations on it must be
         # atomic. POSIX's atomic rename comes in handy.
         write = not sys.dont_write_bytecode
-        cache_dir = os.path.join(fn_pypath.dirname, "__pycache__")
+        cache_dir = os.path.join(os.path.dirname(fn), "__pycache__")
         if write:
             try:
                 os.mkdir(cache_dir)
@@ -132,26 +115,23 @@ class AssertionRewritingHook:
                     # common case) or it's blocked by a non-dir node. In the
                     # latter case, we'll ignore it in _write_pyc.
                     pass
-                elif e in [errno.ENOENT, errno.ENOTDIR]:
+                elif e in {errno.ENOENT, errno.ENOTDIR}:
                     # One of the path components was not a directory, likely
                     # because we're in a zip file.
                     write = False
-                elif e in [errno.EACCES, errno.EROFS, errno.EPERM]:
-                    state.trace("read only directory: %r" % fn_pypath.dirname)
+                elif e in {errno.EACCES, errno.EROFS, errno.EPERM}:
+                    state.trace("read only directory: %r" % os.path.dirname(fn))
                     write = False
                 else:
                     raise
-        cache_name = fn_pypath.basename[:-3] + PYC_TAIL
+        cache_name = os.path.basename(fn)[:-3] + PYC_TAIL
         pyc = os.path.join(cache_dir, cache_name)
         # Notice that even if we're in a read-only directory, I'm going
         # to check for a cached pyc. This may not be optimal...
-        co = _read_pyc(fn_pypath, pyc, state.trace)
+        co = _read_pyc(fn, pyc, state.trace)
         if co is None:
             state.trace("rewriting {!r}".format(fn))
-            source_stat, co = _rewrite_test(self.config, fn_pypath)
-            if co is None:
-                # Probably a SyntaxError in the test.
-                return None
+            source_stat, co = _rewrite_test(fn)
             if write:
                 self._writing_pyc = True
                 try:
@@ -160,13 +140,11 @@ class AssertionRewritingHook:
                     self._writing_pyc = False
         else:
             state.trace("found cached rewritten pyc for {!r}".format(fn))
-        self.modules[name] = co, pyc
-        return self
+        exec(co, module.__dict__)
 
     def _early_rewrite_bailout(self, name, state):
-        """
-        This is a fast way to get out of rewriting modules. Profiling has
-        shown that the call to imp.find_module (inside of the find_module
+        """This is a fast way to get out of rewriting modules. Profiling has
+        shown that the call to PathFinder.find_spec (inside of the find_spec
         from this class) is a major slowdown, so, this method tries to
         filter what we're sure won't be rewritten before getting to it.
         """
@@ -201,10 +179,9 @@ class AssertionRewritingHook:
         state.trace("early skip of rewriting module: {}".format(name))
         return True
 
-    def _should_rewrite(self, name, fn_pypath, state):
+    def _should_rewrite(self, name, fn, state):
         # always rewrite conftest files
-        fn = str(fn_pypath)
-        if fn_pypath.basename == "conftest.py":
+        if os.path.basename(fn) == "conftest.py":
             state.trace("rewriting conftest file: {!r}".format(fn))
             return True
 
@@ -217,8 +194,9 @@ class AssertionRewritingHook:
 
         # modules not passed explicitly on the command line are only
         # rewritten if they match the naming convention for test files
+        fn_path = PurePath(fn)
         for pat in self.fnpats:
-            if fn_pypath.fnmatch(pat):
+            if fnmatch_ex(pat, fn_path):
                 state.trace("matched test file {!r}".format(fn))
                 return True
 
@@ -249,9 +227,10 @@ class AssertionRewritingHook:
             set(names).intersection(sys.modules).difference(self._rewritten_names)
         )
         for name in already_imported:
+            mod = sys.modules[name]
             if not AssertionRewriter.is_rewrite_disabled(
-                sys.modules[name].__doc__ or ""
-            ):
+                mod.__doc__ or ""
+            ) and not isinstance(mod.__loader__, type(self)):
                 self._warn_already_imported(name)
         self._must_rewrite.update(names)
         self._marked_for_rewrite_cache.clear()
@@ -268,45 +247,8 @@ class AssertionRewritingHook:
             stacklevel=5,
         )
 
-    def load_module(self, name):
-        co, pyc = self.modules.pop(name)
-        if name in sys.modules:
-            # If there is an existing module object named 'fullname' in
-            # sys.modules, the loader must use that existing module. (Otherwise,
-            # the reload() builtin will not work correctly.)
-            mod = sys.modules[name]
-        else:
-            # I wish I could just call imp.load_compiled here, but __file__ has to
-            # be set properly. In Python 3.2+, this all would be handled correctly
-            # by load_compiled.
-            mod = sys.modules[name] = imp.new_module(name)
-        try:
-            mod.__file__ = co.co_filename
-            # Normally, this attribute is 3.2+.
-            mod.__cached__ = pyc
-            mod.__loader__ = self
-            # Normally, this attribute is 3.4+
-            mod.__spec__ = spec_from_file_location(name, co.co_filename, loader=self)
-            exec(co, mod.__dict__)
-        except:  # noqa
-            if name in sys.modules:
-                del sys.modules[name]
-            raise
-        return sys.modules[name]
-
-    def is_package(self, name):
-        try:
-            fd, fn, desc = self._imp_find_module(name)
-        except ImportError:
-            return False
-        if fd is not None:
-            fd.close()
-        tp = desc[2]
-        return tp == imp.PKG_DIRECTORY
-
     def get_data(self, pathname):
-        """Optional PEP302 get_data API.
-        """
+        """Optional PEP302 get_data API."""
         with open(pathname, "rb") as f:
             return f.read()
 
@@ -314,15 +256,13 @@ class AssertionRewritingHook:
 def _write_pyc(state, co, source_stat, pyc):
     # Technically, we don't have to have the same pyc format as
     # (C)Python, since these "pycs" should never be seen by builtin
-    # import. However, there's little reason deviate, and I hope
-    # sometime to be able to use imp.load_compiled to load them. (See
-    # the comment in load_module above.)
+    # import. However, there's little reason deviate.
     try:
         with atomicwrites.atomic_write(pyc, mode="wb", overwrite=True) as fp:
-            fp.write(imp.get_magic())
+            fp.write(importlib.util.MAGIC_NUMBER)
             # as of now, bytecode header expects 32-bit numbers for size and mtime (#4903)
-            mtime = int(source_stat.mtime) & 0xFFFFFFFF
-            size = source_stat.size & 0xFFFFFFFF
+            mtime = int(source_stat.st_mtime) & 0xFFFFFFFF
+            size = source_stat.st_size & 0xFFFFFFFF
             # "<LL" stands for 2 unsigned longs, little-ending
             fp.write(struct.pack("<LL", mtime, size))
             fp.write(marshal.dumps(co))
@@ -335,35 +275,14 @@ def _write_pyc(state, co, source_stat, pyc):
     return True
 
 
-RN = b"\r\n"
-N = b"\n"
-
-cookie_re = re.compile(r"^[ \t\f]*#.*coding[:=][ \t]*[-\w.]+")
-BOM_UTF8 = "\xef\xbb\xbf"
-
-
-def _rewrite_test(config, fn):
-    """Try to read and rewrite *fn* and return the code object."""
-    state = config._assertstate
-    try:
-        stat = fn.stat()
-        source = fn.read("rb")
-    except EnvironmentError:
-        return None, None
-    try:
-        tree = ast.parse(source, filename=fn.strpath)
-    except SyntaxError:
-        # Let this pop up again in the real import.
-        state.trace("failed to parse: {!r}".format(fn))
-        return None, None
-    rewrite_asserts(tree, fn, config)
-    try:
-        co = compile(tree, fn.strpath, "exec", dont_inherit=True)
-    except SyntaxError:
-        # It's possible that this error is from some bug in the
-        # assertion rewriting, but I don't know of a fast way to tell.
-        state.trace("failed to compile: {!r}".format(fn))
-        return None, None
+def _rewrite_test(fn):
+    """read and rewrite *fn* and return the code object."""
+    stat = os.stat(fn)
+    with open(fn, "rb") as f:
+        source = f.read()
+    tree = ast.parse(source, filename=fn)
+    rewrite_asserts(tree, fn)
+    co = compile(tree, fn, "exec", dont_inherit=True)
     return stat, co
 
 
@@ -378,8 +297,9 @@ def _read_pyc(source, pyc, trace=lambda x: None):
         return None
     with fp:
         try:
-            mtime = int(source.mtime())
-            size = source.size()
+            stat_result = os.stat(source)
+            mtime = int(stat_result.st_mtime)
+            size = stat_result.st_size
             data = fp.read(12)
         except EnvironmentError as e:
             trace("_read_pyc({}): EnvironmentError {}".format(source, e))
@@ -387,7 +307,7 @@ def _read_pyc(source, pyc, trace=lambda x: None):
         # Check for invalid or out of date pyc file.
         if (
             len(data) != 12
-            or data[:4] != imp.get_magic()
+            or data[:4] != importlib.util.MAGIC_NUMBER
             or struct.unpack("<LL", data[4:]) != (mtime & 0xFFFFFFFF, size & 0xFFFFFFFF)
         ):
             trace("_read_pyc(%s): invalid or out of date pyc" % source)
@@ -403,9 +323,9 @@ def _read_pyc(source, pyc, trace=lambda x: None):
         return co
 
 
-def rewrite_asserts(mod, module_path=None, config=None):
+def rewrite_asserts(mod, module_path=None):
     """Rewrite the assert statements in mod."""
-    AssertionRewriter(module_path, config).run(mod)
+    AssertionRewriter(module_path).run(mod)
 
 
 def _saferepr(obj):
@@ -586,10 +506,9 @@ class AssertionRewriter(ast.NodeVisitor):
 
     """
 
-    def __init__(self, module_path, config):
+    def __init__(self, module_path):
         super().__init__()
         self.module_path = module_path
-        self.config = config
 
     def run(self, mod):
         """Find all assert statements in *mod* and rewrite them."""
@@ -758,7 +677,7 @@ class AssertionRewriter(ast.NodeVisitor):
                     "assertion is always true, perhaps remove parentheses?"
                 ),
                 category=None,
-                filename=str(self.module_path),
+                filename=self.module_path,
                 lineno=assert_.lineno,
             )
 
@@ -817,7 +736,7 @@ class AssertionRewriter(ast.NodeVisitor):
         AST_NONE = ast.parse("None").body[0].value
         val_is_none = ast.Compare(node, [ast.Is()], [AST_NONE])
         send_warning = ast.parse(
-            """
+            """\
 from _pytest.warning_types import PytestAssertRewriteWarning
 from warnings import warn_explicit
 warn_explicit(
@@ -827,7 +746,7 @@ warn_explicit(
     lineno={lineno},
 )
             """.format(
-                filename=module_path.strpath, lineno=lineno
+                filename=module_path, lineno=lineno
             )
         ).body
         return ast.If(val_is_none, send_warning, [])
diff --git a/src/_pytest/main.py b/src/_pytest/main.py
index 118fc784a..73648557e 100644
--- a/src/_pytest/main.py
+++ b/src/_pytest/main.py
@@ -2,8 +2,8 @@
 import enum
 import fnmatch
 import functools
+import importlib
 import os
-import pkgutil
 import sys
 import warnings
 
@@ -630,21 +630,15 @@ class Session(nodes.FSCollector):
     def _tryconvertpyarg(self, x):
         """Convert a dotted module name to path."""
         try:
-            loader = pkgutil.find_loader(x)
-        except ImportError:
+            spec = importlib.util.find_spec(x)
+        except (ValueError, ImportError):
             return x
-        if loader is None:
+        if spec is None or spec.origin in {None, "namespace"}:
             return x
-        # This method is sometimes invoked when AssertionRewritingHook, which
-        # does not define a get_filename method, is already in place:
-        try:
-            path = loader.get_filename(x)
-        except AttributeError:
-            # Retrieve path from AssertionRewritingHook:
-            path = loader.modules[x][0].co_filename
-        if loader.is_package(x):
-            path = os.path.dirname(path)
-        return path
+        elif spec.submodule_search_locations:
+            return os.path.dirname(spec.origin)
+        else:
+            return spec.origin
 
     def _parsearg(self, arg):
         """ return (fspath, names) tuple after checking the file exists. """
diff --git a/src/_pytest/pathlib.py b/src/_pytest/pathlib.py
index 3269c25ed..ecc38eb0f 100644
--- a/src/_pytest/pathlib.py
+++ b/src/_pytest/pathlib.py
@@ -294,6 +294,8 @@ def fnmatch_ex(pattern, path):
         name = path.name
     else:
         name = str(path)
+        if path.is_absolute() and not os.path.isabs(pattern):
+            pattern = "*{}{}".format(os.sep, pattern)
     return fnmatch.fnmatch(name, pattern)
 
 
diff --git a/src/_pytest/pytester.py b/src/_pytest/pytester.py
index 6b304ad9f..2068761fa 100644
--- a/src/_pytest/pytester.py
+++ b/src/_pytest/pytester.py
@@ -1,5 +1,6 @@
 """(disabled by default) support for testing pytest and pytest plugins."""
 import gc
+import importlib
 import os
 import platform
 import re
@@ -16,7 +17,6 @@ import py
 import pytest
 from _pytest._code import Source
 from _pytest._io.saferepr import saferepr
-from _pytest.assertion.rewrite import AssertionRewritingHook
 from _pytest.capture import MultiCapture
 from _pytest.capture import SysCapture
 from _pytest.main import ExitCode
@@ -787,6 +787,11 @@ class Testdir:
 
         :return: a :py:class:`HookRecorder` instance
         """
+        # (maybe a cpython bug?) the importlib cache sometimes isn't updated
+        # properly between file creation and inline_run (especially if imports
+        # are interspersed with file creation)
+        importlib.invalidate_caches()
+
         plugins = list(plugins)
         finalizers = []
         try:
@@ -796,18 +801,6 @@ class Testdir:
                 mp_run.setenv(k, v)
             finalizers.append(mp_run.undo)
 
-            # When running pytest inline any plugins active in the main test
-            # process are already imported.  So this disables the warning which
-            # will trigger to say they can no longer be rewritten, which is
-            # fine as they have already been rewritten.
-            orig_warn = AssertionRewritingHook._warn_already_imported
-
-            def revert_warn_already_imported():
-                AssertionRewritingHook._warn_already_imported = orig_warn
-
-            finalizers.append(revert_warn_already_imported)
-            AssertionRewritingHook._warn_already_imported = lambda *a: None
-
             # Any sys.module or sys.path changes done while running pytest
             # inline should be reverted after the test run completes to avoid
             # clashing with later inline tests run within the same pytest test,
diff --git a/testing/acceptance_test.py b/testing/acceptance_test.py
index 60cc21c4a..3eb7752a4 100644
--- a/testing/acceptance_test.py
+++ b/testing/acceptance_test.py
@@ -633,6 +633,19 @@ class TestInvocationVariants:
 
         result.stdout.fnmatch_lines(["collected*0*items*/*1*errors"])
 
+    def test_pyargs_only_imported_once(self, testdir):
+        pkg = testdir.mkpydir("foo")
+        pkg.join("test_foo.py").write("print('hello from test_foo')\ndef test(): pass")
+        pkg.join("conftest.py").write(
+            "def pytest_configure(config): print('configuring')"
+        )
+
+        result = testdir.runpytest("--pyargs", "foo.test_foo", "-s", syspathinsert=True)
+        # should only import once
+        assert result.outlines.count("hello from test_foo") == 1
+        # should only configure once
+        assert result.outlines.count("configuring") == 1
+
     def test_cmdline_python_package(self, testdir, monkeypatch):
         import warnings
 
diff --git a/testing/test_assertion.py b/testing/test_assertion.py
index eced5461a..0fcfd9f27 100644
--- a/testing/test_assertion.py
+++ b/testing/test_assertion.py
@@ -137,8 +137,8 @@ class TestImportHookInstallation:
             "hamster.py": "",
             "test_foo.py": """\
                 def test_foo(pytestconfig):
-                    assert pytestconfig.pluginmanager.rewrite_hook.find_module('ham') is not None
-                    assert pytestconfig.pluginmanager.rewrite_hook.find_module('hamster') is None
+                    assert pytestconfig.pluginmanager.rewrite_hook.find_spec('ham') is not None
+                    assert pytestconfig.pluginmanager.rewrite_hook.find_spec('hamster') is None
             """,
         }
         testdir.makepyfile(**contents)
diff --git a/testing/test_assertrewrite.py b/testing/test_assertrewrite.py
index 0e6f42239..33c889104 100644
--- a/testing/test_assertrewrite.py
+++ b/testing/test_assertrewrite.py
@@ -1,5 +1,6 @@
 import ast
 import glob
+import importlib
 import os
 import py_compile
 import stat
@@ -117,6 +118,37 @@ class TestAssertionRewrite:
         result = testdir.runpytest_subprocess()
         assert "warnings" not in "".join(result.outlines)
 
+    def test_rewrites_plugin_as_a_package(self, testdir):
+        pkgdir = testdir.mkpydir("plugin")
+        pkgdir.join("__init__.py").write(
+            "import pytest\n"
+            "@pytest.fixture\n"
+            "def special_asserter():\n"
+            "    def special_assert(x, y):\n"
+            "        assert x == y\n"
+            "    return special_assert\n"
+        )
+        testdir.makeconftest('pytest_plugins = ["plugin"]')
+        testdir.makepyfile("def test(special_asserter): special_asserter(1, 2)\n")
+        result = testdir.runpytest()
+        result.stdout.fnmatch_lines(["*assert 1 == 2*"])
+
+    def test_honors_pep_235(self, testdir, monkeypatch):
+        # note: couldn't make it fail on macos with a single `sys.path` entry
+        # note: these modules are named `test_*` to trigger rewriting
+        testdir.tmpdir.join("test_y.py").write("x = 1")
+        xdir = testdir.tmpdir.join("x").ensure_dir()
+        xdir.join("test_Y").ensure_dir().join("__init__.py").write("x = 2")
+        testdir.makepyfile(
+            "import test_y\n"
+            "import test_Y\n"
+            "def test():\n"
+            "    assert test_y.x == 1\n"
+            "    assert test_Y.x == 2\n"
+        )
+        monkeypatch.syspath_prepend(xdir)
+        testdir.runpytest().assert_outcomes(passed=1)
+
     def test_name(self, request):
         def f():
             assert False
@@ -831,8 +863,9 @@ def test_rewritten():
         monkeypatch.setattr(
             hook, "_warn_already_imported", lambda code, msg: warnings.append(msg)
         )
-        hook.find_module("test_remember_rewritten_modules")
-        hook.load_module("test_remember_rewritten_modules")
+        spec = hook.find_spec("test_remember_rewritten_modules")
+        module = importlib.util.module_from_spec(spec)
+        hook.exec_module(module)
         hook.mark_rewrite("test_remember_rewritten_modules")
         hook.mark_rewrite("test_remember_rewritten_modules")
         assert warnings == []
@@ -872,33 +905,6 @@ def test_rewritten():
 
 
 class TestAssertionRewriteHookDetails:
-    def test_loader_is_package_false_for_module(self, testdir):
-        testdir.makepyfile(
-            test_fun="""
-            def test_loader():
-                assert not __loader__.is_package(__name__)
-            """
-        )
-        result = testdir.runpytest()
-        result.stdout.fnmatch_lines(["* 1 passed*"])
-
-    def test_loader_is_package_true_for_package(self, testdir):
-        testdir.makepyfile(
-            test_fun="""
-            def test_loader():
-                assert not __loader__.is_package(__name__)
-
-            def test_fun():
-                assert __loader__.is_package('fun')
-
-            def test_missing():
-                assert not __loader__.is_package('pytest_not_there')
-            """
-        )
-        testdir.mkpydir("fun")
-        result = testdir.runpytest()
-        result.stdout.fnmatch_lines(["* 3 passed*"])
-
     def test_sys_meta_path_munged(self, testdir):
         testdir.makepyfile(
             """
@@ -917,7 +923,7 @@ class TestAssertionRewriteHookDetails:
         state = AssertionState(config, "rewrite")
         source_path = tmpdir.ensure("source.py")
         pycpath = tmpdir.join("pyc").strpath
-        assert _write_pyc(state, [1], source_path.stat(), pycpath)
+        assert _write_pyc(state, [1], os.stat(source_path.strpath), pycpath)
 
         @contextmanager
         def atomic_write_failed(fn, mode="r", overwrite=False):
@@ -979,7 +985,7 @@ class TestAssertionRewriteHookDetails:
         assert len(contents) > strip_bytes
         pyc.write(contents[:strip_bytes], mode="wb")
 
-        assert _read_pyc(source, str(pyc)) is None  # no error
+        assert _read_pyc(str(source), str(pyc)) is None  # no error
 
     def test_reload_is_same(self, testdir):
         # A file that will be picked up during collecting.
@@ -1186,14 +1192,17 @@ def test_rewrite_infinite_recursion(testdir, pytestconfig, monkeypatch):
         # make a note that we have called _write_pyc
         write_pyc_called.append(True)
         # try to import a module at this point: we should not try to rewrite this module
-        assert hook.find_module("test_bar") is None
+        assert hook.find_spec("test_bar") is None
         return original_write_pyc(*args, **kwargs)
 
     monkeypatch.setattr(rewrite, "_write_pyc", spy_write_pyc)
     monkeypatch.setattr(sys, "dont_write_bytecode", False)
 
     hook = AssertionRewritingHook(pytestconfig)
-    assert hook.find_module("test_foo") is not None
+    spec = hook.find_spec("test_foo")
+    assert spec is not None
+    module = importlib.util.module_from_spec(spec)
+    hook.exec_module(module)
     assert len(write_pyc_called) == 1
 
 
@@ -1201,11 +1210,11 @@ class TestEarlyRewriteBailout:
     @pytest.fixture
     def hook(self, pytestconfig, monkeypatch, testdir):
         """Returns a patched AssertionRewritingHook instance so we can configure its initial paths and track
-        if imp.find_module has been called.
+        if PathFinder.find_spec has been called.
         """
-        import imp
+        import importlib.machinery
 
-        self.find_module_calls = []
+        self.find_spec_calls = []
         self.initial_paths = set()
 
         class StubSession:
@@ -1214,22 +1223,22 @@ class TestEarlyRewriteBailout:
             def isinitpath(self, p):
                 return p in self._initialpaths
 
-        def spy_imp_find_module(name, path):
-            self.find_module_calls.append(name)
-            return imp.find_module(name, path)
+        def spy_find_spec(name, path):
+            self.find_spec_calls.append(name)
+            return importlib.machinery.PathFinder.find_spec(name, path)
 
         hook = AssertionRewritingHook(pytestconfig)
         # use default patterns, otherwise we inherit pytest's testing config
         hook.fnpats[:] = ["test_*.py", "*_test.py"]
-        monkeypatch.setattr(hook, "_imp_find_module", spy_imp_find_module)
+        monkeypatch.setattr(hook, "_find_spec", spy_find_spec)
         hook.set_session(StubSession())
         testdir.syspathinsert()
         return hook
 
     def test_basic(self, testdir, hook):
         """
-        Ensure we avoid calling imp.find_module when we know for sure a certain module will not be rewritten
-        to optimize assertion rewriting (#3918).
+        Ensure we avoid calling PathFinder.find_spec when we know for sure a certain
+        module will not be rewritten to optimize assertion rewriting (#3918).
         """
         testdir.makeconftest(
             """
@@ -1244,24 +1253,24 @@ class TestEarlyRewriteBailout:
         self.initial_paths.add(foobar_path)
 
         # conftest files should always be rewritten
-        assert hook.find_module("conftest") is not None
-        assert self.find_module_calls == ["conftest"]
+        assert hook.find_spec("conftest") is not None
+        assert self.find_spec_calls == ["conftest"]
 
         # files matching "python_files" mask should always be rewritten
-        assert hook.find_module("test_foo") is not None
-        assert self.find_module_calls == ["conftest", "test_foo"]
+        assert hook.find_spec("test_foo") is not None
+        assert self.find_spec_calls == ["conftest", "test_foo"]
 
         # file does not match "python_files": early bailout
-        assert hook.find_module("bar") is None
-        assert self.find_module_calls == ["conftest", "test_foo"]
+        assert hook.find_spec("bar") is None
+        assert self.find_spec_calls == ["conftest", "test_foo"]
 
         # file is an initial path (passed on the command-line): should be rewritten
-        assert hook.find_module("foobar") is not None
-        assert self.find_module_calls == ["conftest", "test_foo", "foobar"]
+        assert hook.find_spec("foobar") is not None
+        assert self.find_spec_calls == ["conftest", "test_foo", "foobar"]
 
     def test_pattern_contains_subdirectories(self, testdir, hook):
         """If one of the python_files patterns contain subdirectories ("tests/**.py") we can't bailout early
-        because we need to match with the full path, which can only be found by calling imp.find_module.
+        because we need to match with the full path, which can only be found by calling PathFinder.find_spec
         """
         p = testdir.makepyfile(
             **{
@@ -1273,8 +1282,8 @@ class TestEarlyRewriteBailout:
         )
         testdir.syspathinsert(p.dirpath())
         hook.fnpats[:] = ["tests/**.py"]
-        assert hook.find_module("file") is not None
-        assert self.find_module_calls == ["file"]
+        assert hook.find_spec("file") is not None
+        assert self.find_spec_calls == ["file"]
 
     @pytest.mark.skipif(
         sys.platform.startswith("win32"), reason="cannot remove cwd on Windows"
diff --git a/testing/test_pathlib.py b/testing/test_pathlib.py
index 8ac404070..45daeaed7 100644
--- a/testing/test_pathlib.py
+++ b/testing/test_pathlib.py
@@ -1,3 +1,4 @@
+import os.path
 import sys
 
 import py
@@ -53,6 +54,10 @@ class TestPort:
     def test_matching(self, match, pattern, path):
         assert match(pattern, path)
 
+    def test_matching_abspath(self, match):
+        abspath = os.path.abspath(os.path.join("tests/foo.py"))
+        assert match("tests/foo.py", abspath)
+
     @pytest.mark.parametrize(
         "pattern, path",
         [