info: enable PEP 517 fallback builds by default

This change ensures that PEP 517 fallback builds are enabled by default
for when metadata inspection and setup.{py,cfg} parsing fails. This is
required in order to ensure that package requirements are correctly
identified for packages beyond first level dependencies.

Resolves: #2807

poetry/inspection/info.py

@@ -488,15 +488,16 @@ class PackageInfo:
 
     @classmethod
     def from_directory(
-        cls, path, allow_build=False
+        cls, path, disable_build=False
     ):  # type: (Path, bool) -> PackageInfo
         """
-        Generate package information from a package source directory. When `allow_build` is enabled and
+        Generate package information from a package source directory. If `disable_build` is not `True` and
         introspection of all available metadata fails, the package is attempted to be build in an isolated
         environment so as to generate required metadata.
 
         :param path: Path to generate package information from.
-        :param allow_build: If enabled, as a fallback, build the project to gather metadata.
+        :param disable_build: If not `True` and setup reader fails, PEP 517 isolated build is attempted in
+            order to gather metadata.
         """
         project_package = cls._get_poetry_package(path)
         if project_package:
@@ -509,7 +510,7 @@ class PackageInfo:
             return info
 
         try:
-            if not allow_build:
+            if disable_build:
                 return cls.from_setup_files(path)
             return cls._pep517_metadata(path)
         except PackageInfoError as e:

poetry/puzzle/provider.py

@@ -308,9 +308,9 @@ class Provider:
     def get_package_from_directory(
         cls, directory, name=None
     ):  # type: (Path, Optional[str]) -> Package
-        package = PackageInfo.from_directory(
-            path=directory, allow_build=True
-        ).to_package(root_dir=directory)
+        package = PackageInfo.from_directory(path=directory).to_package(
+            root_dir=directory
+        )
 
         if name and name != package.name:
             # For now, the dependency's name must match the actual package's name

tests/conftest.py

@@ -11,6 +11,7 @@ import pytest
 from poetry.config.config import Config as BaseConfig
 from poetry.config.dict_config_source import DictConfigSource
 from poetry.inspection.info import PackageInfo
+from poetry.inspection.info import PackageInfoError
 from poetry.utils._compat import Path
 from poetry.utils.env import EnvManager
 from poetry.utils.env import VirtualEnv
@@ -82,9 +83,16 @@ def download_mock(mocker):
 
 @pytest.fixture(autouse=True)
 def pep517_metadata_mock(mocker):
+    @classmethod  # noqa
+    def _pep517_metadata(cls, path):
+        try:
+            return PackageInfo.from_setup_files(path)
+        except PackageInfoError:
+            pass
+        return PackageInfo(name="demo", version="0.1.2")
+
     mocker.patch(
-        "poetry.inspection.info.PackageInfo._pep517_metadata",
-        return_value=PackageInfo(name="demo", version="0.1.2"),
+        "poetry.inspection.info.PackageInfo._pep517_metadata", _pep517_metadata,
     )
 
 

tests/inspection/test_info.py

@@ -121,7 +121,9 @@ def test_info_from_bdist(demo_wheel):
 
 
 def test_info_from_poetry_directory():
-    info = PackageInfo.from_directory(FIXTURE_DIR_INSPECTIONS / "demo")
+    info = PackageInfo.from_directory(
+        FIXTURE_DIR_INSPECTIONS / "demo", disable_build=True
+    )
     demo_check_info(info)
 
 
@@ -146,7 +148,7 @@ def test_info_from_setup_cfg(demo_setup_cfg):
 
 def test_info_no_setup_pkg_info_no_deps():
     info = PackageInfo.from_directory(
-        FIXTURE_DIR_INSPECTIONS / "demo_no_setup_pkg_info_no_deps"
+        FIXTURE_DIR_INSPECTIONS / "demo_no_setup_pkg_info_no_deps", disable_build=True,
     )
     assert info.name == "demo"
     assert info.version == "0.1.0"
@@ -156,7 +158,7 @@ def test_info_no_setup_pkg_info_no_deps():
 @pytest.mark.skipif(not PY35, reason="Parsing of setup.py is skipped for Python < 3.5")
 def test_info_setup_simple(mocker, demo_setup):
     spy = mocker.spy(VirtualEnv, "run")
-    info = PackageInfo.from_directory(demo_setup, allow_build=True)
+    info = PackageInfo.from_directory(demo_setup)
     assert spy.call_count == 0
     demo_check_info(info, requires_dist={"package"})
 
@@ -167,7 +169,7 @@ def test_info_setup_simple(mocker, demo_setup):
 )
 def test_info_setup_simple_py2(mocker, demo_setup):
     spy = mocker.spy(VirtualEnv, "run")
-    info = PackageInfo.from_directory(demo_setup, allow_build=True)
+    info = PackageInfo.from_directory(demo_setup)
     assert spy.call_count == 2
     demo_check_info(info, requires_dist={"package"})
 
@@ -175,13 +177,13 @@ def test_info_setup_simple_py2(mocker, demo_setup):
 @pytest.mark.skipif(not PY35, reason="Parsing of setup.cfg is skipped for Python < 3.5")
 def test_info_setup_cfg(mocker, demo_setup_cfg):
     spy = mocker.spy(VirtualEnv, "run")
-    info = PackageInfo.from_directory(demo_setup_cfg, allow_build=True)
+    info = PackageInfo.from_directory(demo_setup_cfg)
     assert spy.call_count == 0
     demo_check_info(info, requires_dist={"package"})
 
 
 def test_info_setup_complex(demo_setup_complex):
-    info = PackageInfo.from_directory(demo_setup_complex, allow_build=True)
+    info = PackageInfo.from_directory(demo_setup_complex)
     demo_check_info(info, requires_dist={"package"})
 
 
@@ -193,20 +195,18 @@ def test_info_setup_complex_pep517_error(mocker, demo_setup_complex):
     )
 
     with pytest.raises(PackageInfoError):
-        PackageInfo.from_directory(demo_setup_complex, allow_build=True)
+        PackageInfo.from_directory(demo_setup_complex)
 
 
 def test_info_setup_complex_pep517_legacy(demo_setup_complex_pep517_legacy):
-    info = PackageInfo.from_directory(
-        demo_setup_complex_pep517_legacy, allow_build=True
-    )
+    info = PackageInfo.from_directory(demo_setup_complex_pep517_legacy)
     demo_check_info(info, requires_dist={"package"})
 
 
 @pytest.mark.skipif(not PY35, reason="Parsing of setup.py is skipped for Python < 3.5")
 def test_info_setup_complex_disable_build(mocker, demo_setup_complex):
     spy = mocker.spy(VirtualEnv, "run")
-    info = PackageInfo.from_directory(demo_setup_complex, allow_build=False)
+    info = PackageInfo.from_directory(demo_setup_complex, disable_build=True)
     assert spy.call_count == 0
     assert info.name == "demo"
     assert info.version == "0.1.0"