1 files changed, 61 insertions, 0 deletions
diff --git a/tests/test_stringio.py b/tests/test_stringio.py
new file mode 100644
index 0000000..89e784f
--- /dev/null
+++ b/tests/test_stringio.py
@@ -0,0 +1,61 @@
+from io import StringIO
+
+ENCODING = 'utf-8'
+
+S0 = 'hello world, Umlauts: äöüßÄÖÜ, Chinese: 四是四，十是十，十四是十四，四十是四十，四十四隻不識字之石獅子是死的'
+S0_BYTES = 'fe fi foe fam'.encode(ENCODING)
+
+#print("###", StringIO, "###")
+
+
+def test_001_text():
+    # If we throw unicode into the StringIO buffer, we'll
+    # get unicode out of it.
+    assert isinstance(S0, str)
+    buf = StringIO()
+    print(S0, file=buf, end="")
+    s1 = buf.getvalue()
+    assert isinstance(S0, type(s1))
+    assert S0 == s1
+    assert isinstance(s1, str)
+
+
+def test_002_bytes():
+    buf = StringIO()
+    print(S0_BYTES, file=buf, end="")
+    s1 = buf.getvalue()
+
+    # In Python 3 StringIO *ALWAYS* returns str (=text=unicode) !
+    # Even if we originally write bytes into the buffer, the value
+    # we get out of it has type str!
+
+    # Input is bytes
+    assert isinstance(S0_BYTES, bytes)
+    # Output is NOT bytes...
+    assert not isinstance(S0_BYTES, type(s1))
+    assert not isinstance(s1, bytes)
+    # ...but str!
+    assert isinstance(s1, str)
+    # So the contents are not equal!
+    assert S0_BYTES != s1
+    # StringIO coerced bytes into str:
+    # b'xyz' ---> "b'xyz'"
+    assert str(S0_BYTES) == s1
+    # See, the type info is literally present in the output str!
+    assert "b'" + str(S0_BYTES, encoding=ENCODING) + "'" == s1
+    # Coercion is NOT decoding!
+    assert S0_BYTES.decode(ENCODING) != s1
+    assert str(S0_BYTES, encoding=ENCODING) != s1
+    # These are the same
+    assert S0_BYTES.decode(ENCODING) == str(S0_BYTES, encoding=ENCODING)
+    # Additional note:
+    # If we do not specify an encoding when we create a StringIO
+    # buffer, Python 3 automatically uses the locale's preferred
+    # encoding: locale.getpreferredencoding()
+    # Cf. http://docs.python.org/release/3.0.1/library/io.html#io.TextIOWrapper
+    # In my case this is the same encoding as the encoding of this source file,
+    # namely UTF-8. If on your system both encodings are different, you may
+    # encounter other results than the above.
+    #
+    # In Python 3.2 the signature of StringIO() has changed. It is no more
+    # possible to specify an encoding here.