[python] [tests] Support overriding library path via environment

[mgorny]

Summary

Support a new CLANG_LIBRARY_PATH environment variable for the Python
binding tests. This variable can be used to force the bindings to load
libclang.* from a specific directory.

I plan to use this when integrating Python binding tests with the CMake
build system. Currently, those tests load libclang.so from default
search paths, so I would have to rely on platform-specific mechanics
such as LD_LIBRARY_PATH. Instead of copying the whole logic necessary
to handle platform differences into yet another place, it's easier to
just add a dedicated variable for this purpose.

[mgorny]

(also included README update)

[mgorny]

To avoid consumers of the bindings, I've changed the patch to set the path only through tests. As a result, the binding API is unchanged.

[mgorny]

Gentle ping.

cfe/trunk/bindings/python/README.txt

 //===----------------------------------------------------------------------===//
 // Clang Python Bindings
 //===----------------------------------------------------------------------===//
 
 This directory implements Python bindings for Clang.
 
-You may need to alter LD_LIBRARY_PATH so that the Clang library can be
+You may need to set CLANG_LIBRARY_PATH so that the Clang library can be
 found. The unit tests are designed to be run with any standard test
 runner. For example:
 --
 $ env PYTHONPATH=$(echo ~/llvm/tools/clang/bindings/python/) \
-      LD_LIBRARY_PATH=$(llvm-config --libdir) \
+      CLANG_LIBRARY_PATH=$(llvm-config --libdir) \
   python -m unittest discover -v
 tests.cindex.test_index.test_create ... ok
 ...
 
 OK
 --

cfe/trunk/bindings/python/tests/cindex/test_access_specifiers.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
 
 from clang.cindex import AccessSpecifier
 from clang.cindex import Cursor
 from clang.cindex import TranslationUnit
 
 from .util import get_cursor
 from .util import get_tu
 

cfe/trunk/bindings/python/tests/cindex/test_cdb.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import CompilationDatabase
 from clang.cindex import CompilationDatabaseError
 from clang.cindex import CompileCommands
 from clang.cindex import CompileCommand
 import os
 import gc
 import unittest
 import sys

cfe/trunk/bindings/python/tests/cindex/test_code_completion.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import TranslationUnit
 
 import unittest
 
 
 class TestCodeCompletion(unittest.TestCase):
     def check_completion_results(self, cr, expected):
         self.assertIsNotNone(cr)

cfe/trunk/bindings/python/tests/cindex/test_comment.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import TranslationUnit
 from tests.cindex.util import get_cursor
 
 import unittest
 
 
 class TestComment(unittest.TestCase):
     def test_comment(self):

cfe/trunk/bindings/python/tests/cindex/test_cursor.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 import ctypes
 import gc
 import unittest
 
 from clang.cindex import AvailabilityKind
 from clang.cindex import CursorKind
 from clang.cindex import TemplateArgumentKind
 from clang.cindex import TranslationUnit

cfe/trunk/bindings/python/tests/cindex/test_cursor_kind.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import CursorKind
 
 import unittest
 
 
 class TestCursorKind(unittest.TestCase):
     def test_name(self):
         self.assertTrue(CursorKind.UNEXPOSED_DECL.name is 'UNEXPOSED_DECL')

cfe/trunk/bindings/python/tests/cindex/test_diagnostics.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import *
 from .util import get_tu
 
 import unittest
 
 
 # FIXME: We need support for invalid translation units to test better.
 

cfe/trunk/bindings/python/tests/cindex/test_exception_specification_kind.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 import clang.cindex
 from clang.cindex import ExceptionSpecificationKind
 from .util import get_tu
 
 import unittest
 
 
 def find_function_declarations(node, declarations=[]):

cfe/trunk/bindings/python/tests/cindex/test_file.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import Index, File
 
 import unittest
 
 
 class TestFile(unittest.TestCase):
     def test_file(self):
         index = Index.create()
         tu = index.parse('t.c', unsaved_files = [('t.c', "")])
         file = File.from_name(tu, "t.c")
         self.assertEqual(str(file), "t.c")
         self.assertEqual(file.name, "t.c")
         self.assertEqual(repr(file), "<File: t.c>")

cfe/trunk/bindings/python/tests/cindex/test_index.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import *
 import os
 import unittest
 
 
 kInputsDir = os.path.join(os.path.dirname(__file__), 'INPUTS')
 
 

cfe/trunk/bindings/python/tests/cindex/test_linkage.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import LinkageKind
 from clang.cindex import Cursor
 from clang.cindex import TranslationUnit
 
 from .util import get_cursor
 from .util import get_tu
 
 import unittest

cfe/trunk/bindings/python/tests/cindex/test_location.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import Cursor
 from clang.cindex import File
 from clang.cindex import SourceLocation
 from clang.cindex import SourceRange
 from .util import get_cursor
 from .util import get_tu
 
 import unittest

cfe/trunk/bindings/python/tests/cindex/test_tls_kind.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import TLSKind
 from clang.cindex import Cursor
 from clang.cindex import TranslationUnit
 
 from .util import get_cursor
 from .util import get_tu
 
 import unittest

cfe/trunk/bindings/python/tests/cindex/test_token_kind.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import TokenKind
 
 import unittest
 
 
 class TestTokenKind(unittest.TestCase):
     def test_constructor(self):
         """Ensure TokenKind constructor works as expected."""

cfe/trunk/bindings/python/tests/cindex/test_tokens.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from clang.cindex import CursorKind
 from clang.cindex import Index
 from clang.cindex import SourceLocation
 from clang.cindex import SourceRange
 from clang.cindex import TokenKind
 
 from .util import get_tu
 

cfe/trunk/bindings/python/tests/cindex/test_translation_unit.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 from contextlib import contextmanager
 import gc
 import os
 import tempfile
 import unittest
 
 from clang.cindex import CursorKind
 from clang.cindex import Cursor

cfe/trunk/bindings/python/tests/cindex/test_type.py

+import os
+from clang.cindex import Config
+if 'CLANG_LIBRARY_PATH' in os.environ:
+    Config.set_library_path(os.environ['CLANG_LIBRARY_PATH'])
+
 import gc
 import unittest
 
 from clang.cindex import CursorKind
 from clang.cindex import TranslationUnit
 from clang.cindex import TypeKind
 from .util import get_cursor
 from .util import get_tu