Find Python environments on Windows using the registry

appveyor.yml

@@ -2,83 +2,83 @@ environment:
   matrix:
   - TOXENV: py27
     PYTHON_PATH: C:\Python27
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python27\python.exe
+    JEDI_TEST_ENVIRONMENT: 27
   - TOXENV: py27
     PYTHON_PATH: C:\Python27
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python33\python.exe
+    JEDI_TEST_ENVIRONMENT: 33
   - TOXENV: py27
     PYTHON_PATH: C:\Python27
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python34\python.exe
+    JEDI_TEST_ENVIRONMENT: 34
   - TOXENV: py27
     PYTHON_PATH: C:\Python27
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python35\python.exe
+    JEDI_TEST_ENVIRONMENT: 35
   - TOXENV: py27
     PYTHON_PATH: C:\Python27
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python36\python.exe
+    JEDI_TEST_ENVIRONMENT: 36
 
   - TOXENV: py33
     PYTHON_PATH: C:\Python33
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python27\python.exe
+    JEDI_TEST_ENVIRONMENT: 27
   - TOXENV: py33
     PYTHON_PATH: C:\Python33
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python33\python.exe
+    JEDI_TEST_ENVIRONMENT: 33
   - TOXENV: py33
     PYTHON_PATH: C:\Python33
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python34\python.exe
+    JEDI_TEST_ENVIRONMENT: 34
   - TOXENV: py33
     PYTHON_PATH: C:\Python33
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python35\python.exe
+    JEDI_TEST_ENVIRONMENT: 35
   - TOXENV: py33
     PYTHON_PATH: C:\Python33
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python36\python.exe
+    JEDI_TEST_ENVIRONMENT: 36
 
   - TOXENV: py34
     PYTHON_PATH: C:\Python34
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python27\python.exe
+    JEDI_TEST_ENVIRONMENT: 27
   - TOXENV: py34
     PYTHON_PATH: C:\Python34
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python33\python.exe
+    JEDI_TEST_ENVIRONMENT: 33
   - TOXENV: py34
     PYTHON_PATH: C:\Python34
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python34\python.exe
+    JEDI_TEST_ENVIRONMENT: 34
   - TOXENV: py34
     PYTHON_PATH: C:\Python34
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python35\python.exe
+    JEDI_TEST_ENVIRONMENT: 35
   - TOXENV: py34
     PYTHON_PATH: C:\Python34
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python36\python.exe
+    JEDI_TEST_ENVIRONMENT: 36
 
   - TOXENV: py35
     PYTHON_PATH: C:\Python35
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python27\python.exe
+    JEDI_TEST_ENVIRONMENT: 27
   - TOXENV: py35
     PYTHON_PATH: C:\Python35
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python33\python.exe
+    JEDI_TEST_ENVIRONMENT: 33
   - TOXENV: py35
     PYTHON_PATH: C:\Python35
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python34\python.exe
+    JEDI_TEST_ENVIRONMENT: 34
   - TOXENV: py35
     PYTHON_PATH: C:\Python35
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python35\python.exe
+    JEDI_TEST_ENVIRONMENT: 35
   - TOXENV: py35
     PYTHON_PATH: C:\Python35
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python36\python.exe
+    JEDI_TEST_ENVIRONMENT: 36
 
   - TOXENV: py36
     PYTHON_PATH: C:\Python36
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python27\python.exe
+    JEDI_TEST_ENVIRONMENT: 27
   - TOXENV: py36
     PYTHON_PATH: C:\Python36
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python33\python.exe
+    JEDI_TEST_ENVIRONMENT: 33
   - TOXENV: py36
     PYTHON_PATH: C:\Python36
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python34\python.exe
+    JEDI_TEST_ENVIRONMENT: 34
   - TOXENV: py36
     PYTHON_PATH: C:\Python36
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python35\python.exe
+    JEDI_TEST_ENVIRONMENT: 35
   - TOXENV: py36
     PYTHON_PATH: C:\Python36
-    JEDI_TEST_ENVIRONMENT_EXECUTABLE: C:\Python36\python.exe
+    JEDI_TEST_ENVIRONMENT: 36
 install:
   - set PATH=%PYTHON_PATH%;%PYTHON_PATH%\Scripts;%PATH%
   - pip install --disable-pip-version-check --user --upgrade pip

conftest.py

@@ -87,10 +87,6 @@ def clean_jedi_cache(request):
 
 @pytest.fixture(scope='session')
 def environment(request):
-    python = os.environ.get('JEDI_TEST_ENVIRONMENT_EXECUTABLE')
-    if python:
-        return get_python_environment(python)
-
     version = request.config.option.env
     if version is None:
         version = os.environ.get('JEDI_TEST_ENVIRONMENT', str(py_version))

jedi/api/environment.py

@@ -163,12 +163,41 @@ def find_python_environments():
                 pass
 
 
-def get_python_environment(python_name):
+# TODO: the logic to find the Python prefix is much more complicated than that.
-    exe = find_executable(python_name)
+# See Modules/getpath.c for UNIX and PC/getpathp.c for Windows in CPython's
-    if exe is None:
+# source code. A solution would be to deduce it by running the Python
-        raise InvalidPythonEnvironment("This executable doesn't exist.")
+# interpreter and printing the value of sys.prefix.
-    path = os.path.dirname(os.path.dirname(exe))
+def _get_python_prefix(executable):
-    return Environment(path, exe)
+    if os.name != 'nt':
+        return os.path.dirname(os.path.dirname(executable))
+    landmark = os.path.join('Lib', 'os.py')
+    prefix = os.path.dirname(executable)
+    while prefix:
+        if os.path.join(prefix, landmark):
+            return prefix
+        prefix = os.path.dirname(prefix)
+    raise InvalidPythonEnvironment(
+        "Cannot find prefix of executable %s." % executable)
+
+
+# TODO: this function should probably return a list of environments since
+# multiple Python installations can be found on a system for the same version.
+def get_python_environment(python):
+    """
+    Return the first Python environment found for a given path or for a string
+    of the form 'pythonX.Y' where X and Y are the major and minor versions of
+    Python.
+    """
+    exe = find_executable(python)
+    if exe:
+        return Environment(_get_python_prefix(exe), exe)
+    if os.name == 'nt':
+        match = re.search('python(\d+\.\d+)$', python)
+        if match:
+            version = match.group(1)
+            for prefix, exe in _get_executables_from_windows_registry(version):
+                return Environment(prefix, exe)
+    raise InvalidPythonEnvironment("Cannot find executable %s." % python)
 
 
 def create_environment(path):
@@ -206,6 +235,33 @@ def _get_executable_path(path, safe=True):
     return python
 
 
+def _get_executables_from_windows_registry(version):
+    # The winreg module is named _winreg on Python 2.
+    try:
+      import winreg
+    except ImportError:
+      import _winreg as winreg
+
+    # TODO: support Python Anaconda.
+    sub_keys = [
+      r'SOFTWARE\Python\PythonCore\{version}\InstallPath',
+      r'SOFTWARE\Wow6432Node\Python\PythonCore\{version}\InstallPath',
+      r'SOFTWARE\Python\PythonCore\{version}-32\InstallPath',
+      r'SOFTWARE\Wow6432Node\Python\PythonCore\{version}-32\InstallPath'
+    ]
+    for root_key in [winreg.HKEY_CURRENT_USER, winreg.HKEY_LOCAL_MACHINE]:
+        for sub_key in sub_keys:
+            sub_key = sub_key.format(version=version)
+            try:
+                with winreg.OpenKey(root_key, sub_key) as key:
+                    prefix = winreg.QueryValueEx(key, '')[0]
+                    exe = os.path.join(prefix, 'python.exe')
+                    if os.path.isfile(exe):
+                        yield prefix, exe
+            except WindowsError:
+                pass
+
+
 def _is_safe(executable_path):
     real_path = os.path.realpath(executable_path)
     if _is_admin():

test/test_api/test_environment.py

@@ -6,8 +6,8 @@ import pytest
 
 import jedi
 from jedi._compatibility import py_version
-from jedi.api.environment import Environment, get_default_environment, \
+from jedi.api.environment import get_default_environment, \
-    InvalidPythonEnvironment, find_python_environments
+    get_python_environment, InvalidPythonEnvironment, find_python_environments
 
 
 def test_sys_path():
@@ -24,24 +24,21 @@ def test_find_python_environments():
         assert parser_version[:2] == env.version_info[:2]
 
 
-# Cannot deduce the environment from Python executable name on Windows.
-@pytest.mark.skipif("os.name == 'nt'")
 @pytest.mark.parametrize(
     'version',
     ['2.7', '3.3', '3.4', '3.5', '3.6', '3.7']
 )
 def test_versions(version):
-    executable = 'python' + version
     try:
-        env = Environment('some path', executable)
+        env = get_python_environment('python' + version)
     except InvalidPythonEnvironment:
         if int(version.replace('.', '')) == py_version:
             # At least the current version has to work
             raise
-        return
+        pytest.skip()
 
-    sys_path = env.get_sys_path()
+    assert version == str(env.version_info[0]) + '.' + str(env.version_info[1])
-    assert any(executable in p for p in sys_path)
+    assert env.get_sys_path()
 
 
 def test_load_module(evaluator):