Use utils.pip for executor installs

poetry/installation/executor.py

@@ -22,6 +22,7 @@
 from poetry.utils.helpers import safe_rmtree
 from poetry.utils.pip import pip_editable_install
 
+from ..utils.pip import pip_install
 from .authenticator import Authenticator
 from .chef import Chef
 from .chooser import Chooser
@@ -419,12 +420,9 @@ def _install(self, operation):
             message=operation_message,
         )
         self._write(operation, message)
-
-        args = ["install", "--no-deps", str(archive)]
-        if operation.job_type == "update":
-            args.insert(2, "-U")
-
-        return self.run_pip(*args)
+        return pip_install(
+            str(archive), self._env, upgrade=operation.job_type == "update"
+        )
 
     def _update(self, operation):
         return self._install(operation)
@@ -479,8 +477,6 @@ def _install_directory(self, operation):
         else:
             req = os.path.realpath(package.source_url)
 
-        args = ["install", "--no-deps", "-U"]
-
         pyproject = TomlFile(os.path.join(req, "pyproject.toml"))
 
         has_poetry = False
@@ -525,17 +521,12 @@ def _install_directory(self, operation):
                 with builder.setup_py():
                     if package.develop:
                         return pip_editable_install(req, self._env)
-
-                    args.append(req)
-
-                    return self.run_pip(*args)
+                    return pip_install(req, self._env, upgrade=True)
 
         if package.develop:
             return pip_editable_install(req, self._env)
 
-        args.append(req)
-
-        return self.run_pip(*args)
+        return pip_install(req, self._env, upgrade=True)
 
     def _install_git(self, operation):
         from poetry.core.vcs import Git

poetry/utils/pip.py

@@ -1,3 +1,5 @@
+from typing import Union
+
 from poetry.exceptions import PoetryException
 from poetry.utils._compat import Path
 from poetry.utils.env import Env
@@ -6,10 +8,10 @@
 
 def pip_install(
     path, environment, editable=False, deps=False, upgrade=False
-):  # type: (Path, Env, bool, bool, bool) -> None
+):  # type: (Union[Path, str], Env, bool, bool, bool) -> None
     path = Path(path) if isinstance(path, str) else path
 
-    args = ["pip", "install", "--prefix", str(environment.path)]
+    args = ["install", "--prefix", str(environment.path)]
 
     if upgrade:
         args.append("--upgrade")
@@ -26,10 +28,13 @@ def pip_install(
 
     args.append(str(path))
 
+    if path.is_file() and path.suffix == ".whl":
+        return environment.run_pip(*args)
+
     with ephemeral_environment(
         executable=environment.python, pip=True, setuptools=True
     ) as env:
-        return env.run(*args)
+        return env.run("pip", *args)
 
 
 def pip_editable_install(directory, environment):  # type: (Path, Env) -> None

tests/installation/test_executor.py

@@ -60,7 +60,7 @@ def test_execute_executes_a_batch_of_operations(
     mocker, config, pool, io, tmp_dir, mock_file_downloads
 ):
     pip_editable_install = mocker.patch(
-        "poetry.installation.executor.pip_editable_install"
+        "poetry.installation.executor.pip_editable_install", unsafe=not PY36
     )
 
     config = Config()