Demonstrate resources in dists and pexes. (pantsbuild#13315)

[ci skip-rust]

[ci skip-build-wheels]

src/python/pants/backend/python/goals/setup_py.py

@@ -684,6 +684,10 @@ async def get_sources(
     # files() targets aren't owned by a single exported target - they aren't code, so
     # we allow them to be in multiple dists. This is helpful for, e.g., embedding
     # a standard license file in a dist.
+    # TODO: This doesn't actually work, the generated setup.py has no way of referencing
+    #  these, since they aren't in a package, so they won't get included in the built dists.
+    # There is a separate `license_files()` setup.py kwarg that we should use for this
+    # special case (see https://setuptools.pypa.io/en/latest/references/keywords.html).
     file_targets = targets_with_sources_types(
         [FileSourceField], transitive_targets.closure, union_membership
     )

testprojects/src/python/hello/BUILD

@@ -2,3 +2,15 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 python_sources()
+
+resources(name="resource", sources=["dist_resource.txt"])
+
+python_distribution(
+    name="hello-dist",
+    dependencies=["testprojects/src/python/hello/greet", ":resource"],
+    provides=setup_py(
+        name="hello-dist",
+        version="0.0.1",
+        zip_safe=True,
+    ),
+)

testprojects/src/python/hello/dist_resource.txt

@@ -0,0 +1 @@
+A resource to embed in the dist.

testprojects/src/python/hello/greet/BUILD

@@ -1,4 +1,9 @@
 # Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
-python_sources()
+resources(
+    name="greeting",
+    sources=["greeting.txt"],
+)
+
+python_sources(dependencies=[":greeting"])

testprojects/src/python/hello/greet/greet.py

@@ -1,9 +1,12 @@
 # Copyright 2014 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
+import pkgutil
+
 from colors import green
 
 
 def greet(greetee):
     """Given the name, return a greeting for a person of that name."""
-    return green("Hello, {}!".format(greetee))
+    greeting = pkgutil.get_data(__name__, "greeting.txt").decode().strip()
+    return green("{}, {}!".format(greeting, greetee))

testprojects/src/python/hello/greet/greeting.txt

@@ -0,0 +1 @@
+Hello

tests/python/pants_test/integration/list_integration_test.py

@@ -36,10 +36,15 @@ def test_list_testproject() -> None:
     assert pants_run.stdout.strip() == "\n".join(
         [
             "testprojects/src/python/hello:hello",
+            "testprojects/src/python/hello:hello-dist",
+            "testprojects/src/python/hello:resource",
             "testprojects/src/python/hello/__init__.py",
+            "testprojects/src/python/hello/dist_resource.txt:resource",
             "testprojects/src/python/hello/greet:greet",
+            "testprojects/src/python/hello/greet:greeting",
             "testprojects/src/python/hello/greet/__init__.py",
             "testprojects/src/python/hello/greet/greet.py",
+            "testprojects/src/python/hello/greet/greeting.txt:greeting",
             "testprojects/src/python/hello/main:main",
             "testprojects/src/python/hello/main:lib",
             "testprojects/src/python/hello/main/__init__.py:lib",