fix libressl error/refactor some error handling (#3609)

* add libre so I can see the error

* add the libre error needed and refactor error handling a bit

We were historically matching on lib + func + reason, but func is
somewhat unstable so now we match on lib + reason only. Of course, in
this case libressl changed both lib and reason so it wouldn't
have mattered. All error handling from the error queue in
openssl is an illusion

* fix a typo, probably an unneeded branch

* review feedback

* refactor tests to support libressl

insert additional rant about libre here, although admittedly these tests
were assuming stability where openssl itself guarantees none

* better assert, fix flake8

2 files changed, 8 insertions, 15 deletions

diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index 20c073a4..e857ff61 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -127,10 +127,7 @@ class TestOpenSSL(object):
     def test_error_strings_loaded(self):
         # returns a value in a static buffer
         err = backend._lib.ERR_error_string(101183626, backend._ffi.NULL)
-        assert backend._ffi.string(err) == (
-            b"error:0607F08A:digital envelope routines:EVP_EncryptFinal_ex:"
-            b"data not multiple of block length"
-        )
+        assert b"data not multiple of block length" in backend._ffi.string(err)
 
     def test_unknown_error_in_cipher_finalize(self):
         cipher = Cipher(AES(b"\0" * 16), CBC(b"\0" * 16), backend=backend)
diff --git a/tests/hazmat/bindings/test_openssl.py b/tests/hazmat/bindings/test_openssl.py
index 9b0da67c..488f64e1 100644
--- a/tests/hazmat/bindings/test_openssl.py
+++ b/tests/hazmat/bindings/test_openssl.py
@@ -8,7 +8,7 @@ import pytest
 
 from cryptography.exceptions import InternalError
 from cryptography.hazmat.bindings.openssl.binding import (
-    Binding, _OpenSSLErrorWithText, _consume_errors, _openssl_assert
+    Binding, _consume_errors, _openssl_assert
 )
 
 
@@ -94,16 +94,12 @@ class TestOpenSSL(object):
         with pytest.raises(InternalError) as exc_info:
             _openssl_assert(b.lib, False)
 
-        assert exc_info.value.err_code == [_OpenSSLErrorWithText(
-            code=101183626,
-            lib=b.lib.ERR_LIB_EVP,
-            func=b.lib.EVP_F_EVP_ENCRYPTFINAL_EX,
-            reason=b.lib.EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH,
-            reason_text=(
-                b'error:0607F08A:digital envelope routines:EVP_EncryptFinal_'
-                b'ex:data not multiple of block length'
-            )
-        )]
+        error = exc_info.value.err_code[0]
+        assert error.code == 101183626
+        assert error.lib == b.lib.ERR_LIB_EVP
+        assert error.func == b.lib.EVP_F_EVP_ENCRYPTFINAL_EX
+        assert error.reason == b.lib.EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH
+        assert b"data not multiple of block length" in error.reason_text
 
     def test_check_startup_errors_are_allowed(self):
         b = Binding()