feat(source/show): notify when PyPI is implicit

Add a notice when all sources are listed and PyPI is implicitly enabled.

src/poetry/console/commands/source/show.py

@@ -26,13 +26,25 @@ class SourceShowCommand(Command):
         ),
     ]
 
+    def notify_implicit_pypi(self) -> None:
+        if not self.poetry.pool.has_repository("pypi"):
+            return
+
+        self.line(
+            "<c1><b>PyPI</> is implicitly enabled as a <b>primary</> source. "
+            "If you wish to disable it, or alter its priority please refer to "
+            "<b>https://python-poetry.org/docs/repositories/#package-sources</>.</>"
+        )
+        self.line("")
+
     def handle(self) -> int:
         sources = self.poetry.get_sources()
         names = self.argument("source")
         lower_names = [name.lower() for name in names]
 
         if not sources:
-            self.line("No sources configured for this project.")
+            self.line("No sources configured for this project.\n")
+            self.notify_implicit_pypi()
             return 0
 
         if names and not any(s.name.lower() in lower_names for s in sources):
@@ -42,10 +54,15 @@ def handle(self) -> int:
             )
             return 1
 
+        is_pypi_implicit = True
+
         for source in sources:
             if names and source.name.lower() not in lower_names:
                 continue
 
+            if source.name.lower() == "pypi":
+                is_pypi_implicit = False
+
             table = self.table(style="compact")
             rows: Rows = [["<info>name</>", f" : <c1>{source.name}</>"]]
             if source.url:
@@ -55,4 +72,7 @@ def handle(self) -> int:
             table.render()
             self.line("")
 
+        if not names and is_pypi_implicit:
+            self.notify_implicit_pypi()
+
         return 0

tests/console/commands/source/test_show.py

@@ -4,6 +4,8 @@
 
 import pytest
 
+from poetry.repositories.pypi_repository import PyPiRepository
+
 
 if TYPE_CHECKING:
     from cleo.testers.command_tester import CommandTester
@@ -178,6 +180,20 @@ def test_source_show_no_sources(tester_no_sources: CommandTester) -> None:
     assert tester_no_sources.status_code == 0
 
 
+def test_source_show_no_sources_implicit_pypi(
+    tester_no_sources: CommandTester, poetry_without_source: Poetry
+) -> None:
+    poetry_without_source.pool.add_repository(PyPiRepository())
+    tester_no_sources.execute("")
+
+    output = tester_no_sources.io.fetch_output().strip()
+
+    assert "No sources configured for this project." in output
+    assert "PyPI is implicitly enabled as a primary source." in output
+
+    assert tester_no_sources.status_code == 0
+
+
 def test_source_show_error(tester: CommandTester) -> None:
     tester.execute("error")
     assert tester.io.fetch_error().strip() == "No source found with name(s): error"