use symlinks in created venv by default on non-windows platforms. (#1069)

* use symlinks in created venv by default on non-windows platforms. Issue #779

* Fixed test for deployments without venv module available.

poetry/utils/env.py

@@ -298,7 +298,13 @@ class Env(object):
         try:
         try:
             from venv import EnvBuilder
             from venv import EnvBuilder
 
 
-            builder = EnvBuilder(with_pip=True)
+            # use the same defaults as python -m venv
+            if os.name == "nt":
+                use_symlinks = False
+            else:
+                use_symlinks = True
+
+            builder = EnvBuilder(with_pip=True, symlinks=use_symlinks)
             build = builder.create
             build = builder.create
         except ImportError:
         except ImportError:
             # We fallback on virtualenv for Python 2.7
             # We fallback on virtualenv for Python 2.7

tests/utils/test_env.py

@@ -24,3 +24,22 @@ def test_env_get_in_project_venv(tmp_dir, environ):
     venv = Env.get(cwd=Path(tmp_dir))
     venv = Env.get(cwd=Path(tmp_dir))
 
 
     assert venv.path == Path(tmp_dir) / ".venv"
     assert venv.path == Path(tmp_dir) / ".venv"
+
+
+def test_env_has_symlinks_on_nix(tmp_dir):
+    venv_path = Path(tmp_dir) / "Virtual Env"
+
+    Env.build_venv(str(venv_path))
+
+    venv = VirtualEnv(venv_path)
+
+    venv_available = False
+    try:
+        from venv import EnvBuilder
+
+        venv_available = True
+    except ImportError:
+        pass
+
+    if os.name != "nt" and venv_available:
+        assert os.path.islink(venv.python)