Fix install of dev package dependencies from lockfile

Override default pip behavior by preemptively installing dev package dependencies
Keep support for tox default skip_install config flag

tox_poetry_installer.py

@@ -9,6 +9,7 @@ from pathlib import Path
 from typing import Dict
 from typing import List
 from typing import Optional
+from typing import Sequence
 from typing import Tuple
 
 from poetry.factory import Factory as PoetryFactory
@@ -34,6 +35,8 @@ __authors__ = ["Ethan Paul <24588726+enpaul@users.noreply.github.com>"]
 
 _PEP508_VERSION_DELIMITERS: Tuple[str, ...] = ("~=", "==", "!=", ">", "<")
 
+_REPORTER_PREFIX = f"[{__title__}]:"
+
 
 class ToxPoetryInstallerException(Exception):
     """Error while installing locked dependencies to the test environment"""
@@ -43,9 +46,24 @@ class NoLockedDependencyError(ToxPoetryInstallerException):
     """Cannot install a package that is not in the lockfile"""
 
 
-def _make_poetry(venv: ToxVirtualEnv) -> Poetry:
-    """Helper to make a poetry object from a toxenv"""
-    return PoetryFactory().create_poetry(venv.envconfig.config.toxinidir)
+def _install_to_venv(
+    poetry: Poetry, venv: ToxVirtualEnv, packages: Sequence[PoetryPackage]
+):
+    """Install a bunch of packages to a virtualenv
+
+    :param poetry: Poetry object the packages were sourced from
+    :param venv: Tox virtual environment to install the packages to
+    :param packages: List of packages to install to the virtual environment
+    """
+    installer = PoetryPipInstaller(
+        env=PoetryVirtualEnv(path=Path(venv.envconfig.envdir)),
+        io=PoetryNullIO(),
+        pool=poetry.pool,
+    )
+
+    for dependency in packages:
+        reporter.verbosity1(f"{_REPORTER_PREFIX} installing {dependency}")
+        installer.install(dependency)
 
 
 def _find_locked_dependencies(
@@ -73,7 +91,7 @@ def _find_locked_dependencies(
         def find_transients(name: str) -> List[PoetryPackage]:
             if name in PoetryProvider.UNSAFE_PACKAGES:
                 reporter.warning(
-                    f"Installing '{name}' using Poetry is not supported; skipping"
+                    f"{_REPORTER_PREFIX} installing '{name}' using Poetry is not supported; skipping"
                 )
                 return []
             transients = [packages[name]]
@@ -112,18 +130,16 @@ def tox_testenv_install_deps(
     :param action: Tox action object
     """
 
-    log_prefix = f"[{__title__}] {venv.name} installdeps:"
-
     if action.name == venv.envconfig.config.isolated_build_env:
         reporter.verbosity1(
-            f"{log_prefix} skipping isolated build environment '{action.name}'"
+            f"{_REPORTER_PREFIX} skipping isolated build environment '{action.name}'"
         )
         return None
 
-    poetry = _make_poetry(venv)
+    poetry = PoetryFactory().create_poetry(venv.envconfig.config.toxinidir)
 
     reporter.verbosity1(
-        f"{log_prefix} loaded project pyproject.toml from {poetry.file}"
+        f"{_REPORTER_PREFIX} loaded project pyproject.toml from {poetry.file}"
     )
 
     dependencies: List[PoetryPackage] = []
@@ -131,17 +147,31 @@ def tox_testenv_install_deps(
         dependencies += _find_locked_dependencies(poetry, env_dependency.name)
 
     reporter.verbosity1(
-        f"{log_prefix} identified {len(dependencies)} dependencies for environment {action.name}"
+        f"{_REPORTER_PREFIX} identified {len(dependencies)} actual dependencies from {len(venv.envconfig.deps)} specified env dependencies"
     )
 
-    installer = PoetryPipInstaller(
-        env=PoetryVirtualEnv(path=Path(venv.envconfig.envdir)),
-        io=PoetryNullIO(),
-        pool=poetry.pool,
+    reporter.verbosity0(
+        f"{_REPORTER_PREFIX} ({venv.name}) installing {len(dependencies)} env dependencies from lockfile"
     )
+    _install_to_venv(poetry, venv, dependencies)
 
-    for dependency in dependencies:
-        reporter.verbosity0(f"{log_prefix} installing {dependency}")
-        installer.install(dependency)
+    if not venv.envconfig.skip_install:
+        reporter.verbosity1(
+            f"{_REPORTER_PREFIX} env specifies 'skip_install = false', performing installation of development package dependencies"
+        )
+
+        primary_dependencies = poetry.locker.locked_repository(False).packages
+        reporter.verbosity1(
+            f"{_REPORTER_PREFIX} identified {len(primary_dependencies)} dependencies of development package"
+        )
+
+        reporter.verbosity0(
+            f"{_REPORTER_PREFIX} ({venv.name}) installing {len(primary_dependencies)} development package dependencies from lockfile"
+        )
+        _install_to_venv(poetry, venv, primary_dependencies)
+    else:
+        reporter.verbosity1(
+            f"{_REPORTER_PREFIX} env specifies 'skip_install = true', skipping installation of top-level package"
+        )
 
     return dependencies