More str/bytes strictness.
diff --git a/Lib/test/test_posixpath.py b/Lib/test/test_posixpath.py
index bcb29df..3eb981d 100644
--- a/Lib/test/test_posixpath.py
+++ b/Lib/test/test_posixpath.py
@@ -143,7 +143,7 @@
     def test_getsize(self):
         f = open(test_support.TESTFN, "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertEqual(posixpath.getsize(test_support.TESTFN), 3)
         finally:
@@ -153,10 +153,10 @@
     def test_time(self):
         f = open(test_support.TESTFN, "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             f = open(test_support.TESTFN, "ab")
-            f.write("bar")
+            f.write(b"bar")
             f.close()
             f = open(test_support.TESTFN, "rb")
             d = f.read()
@@ -175,7 +175,7 @@
         self.assertIs(posixpath.islink(test_support.TESTFN + "1"), False)
         f = open(test_support.TESTFN + "1", "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertIs(posixpath.islink(test_support.TESTFN + "1"), False)
             if hasattr(os, "symlink"):
@@ -195,7 +195,7 @@
         self.assertIs(posixpath.exists(test_support.TESTFN), False)
         f = open(test_support.TESTFN, "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertIs(posixpath.exists(test_support.TESTFN), True)
             self.assertIs(posixpath.lexists(test_support.TESTFN), True)
@@ -209,7 +209,7 @@
         self.assertIs(posixpath.isdir(test_support.TESTFN), False)
         f = open(test_support.TESTFN, "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertIs(posixpath.isdir(test_support.TESTFN), False)
             os.remove(test_support.TESTFN)
@@ -226,7 +226,7 @@
         self.assertIs(posixpath.isfile(test_support.TESTFN), False)
         f = open(test_support.TESTFN, "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertIs(posixpath.isfile(test_support.TESTFN), True)
             os.remove(test_support.TESTFN)
@@ -242,7 +242,7 @@
     def test_samefile(self):
         f = open(test_support.TESTFN + "1", "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertIs(
                 posixpath.samefile(
@@ -267,7 +267,7 @@
                 )
                 os.remove(test_support.TESTFN + "2")
                 f = open(test_support.TESTFN + "2", "wb")
-                f.write("bar")
+                f.write(b"bar")
                 f.close()
                 self.assertIs(
                     posixpath.samefile(
@@ -285,7 +285,7 @@
     def test_samestat(self):
         f = open(test_support.TESTFN + "1", "wb")
         try:
-            f.write("foo")
+            f.write(b"foo")
             f.close()
             self.assertIs(
                 posixpath.samestat(
@@ -308,7 +308,7 @@
                     )
                     os.remove(test_support.TESTFN + "2")
                 f = open(test_support.TESTFN + "2", "wb")
-                f.write("bar")
+                f.write(b"bar")
                 f.close()
                 self.assertIs(
                     posixpath.samestat(