Replace BazelPythonStarlarkApiTest with PythonStarlarkApiTest

The rewritten test is non-Bazel specific and directly checks the sandwich use case.

There's a slight loss in coverage that will be addressed with bazelbuild#7054.

Work towards bazelbuild#1446.

RELNOTES: None
PiperOrigin-RevId: 230002328

src/test/java/com/google/devtools/build/lib/rules/python/BUILD

@@ -18,6 +18,7 @@ test_suite(
         ":PyProviderTest",
         ":PyTestConfiguredTargetTest",
         ":PythonConfigurationTest",
+        ":PythonStarlarkApiTest",
         ":PythonVersionSelectTest",
         ":PythonVersionTest",
     ],
@@ -171,3 +172,15 @@ java_test(
         "//third_party:truth",
     ],
 )
+
+java_test(
+    name = "PythonStarlarkApiTest",
+    srcs = ["PythonStarlarkApiTest.java"],
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib:packages-internal",
+        "//src/main/java/com/google/devtools/build/lib:python-rules",
+        "//src/test/java/com/google/devtools/build/lib:analysis_testutil",
+        "//third_party:junit4",
+        "//third_party:truth",
+    ],
+)

src/test/java/com/google/devtools/build/lib/rules/python/PythonStarlarkApiTest.java

@@ -0,0 +1,105 @@
+// Copyright 2019 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.python;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.devtools.build.lib.analysis.util.BuildViewTestCase;
+import com.google.devtools.build.lib.packages.StructImpl;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests the ability of Starlark code to interact with the Python rules via the py provider. */
+@RunWith(JUnit4.class)
+public class PythonStarlarkApiTest extends BuildViewTestCase {
+
+  // TODO(#7054): Imports aren't propagated correctly. When we fix that, add it to the fields
+  // tested here.
+
+  /** Defines userlib in //pkg:rules.bzl, which acts as a Starlark-defined version of py_library. */
+  private void defineUserlibRule() throws Exception {
+    scratch.file(
+        "pkg/rules.bzl",
+        "def _userlib_impl(ctx):",
+        "    dep_infos = [dep.py for dep in ctx.attr.deps]",
+        "    transitive_sources = depset(",
+        "        direct=ctx.files.srcs,",
+        "        transitive=[py.transitive_sources for py in dep_infos],",
+        "        order='postorder')",
+        "    uses_shared_libraries = \\",
+        "        any([py.uses_shared_libraries for py in dep_infos]) or \\",
+        "        ctx.attr.uses_shared_libraries",
+        "    has_py2_only_sources = \\",
+        "        any([py.has_py2_only_sources for py in dep_infos]) or \\",
+        "        ctx.attr.has_py2_only_sources",
+        "    has_py3_only_sources = \\",
+        "        any([py.has_py3_only_sources for py in dep_infos]) or \\",
+        "        ctx.attr.has_py3_only_sources",
+        "    info = struct(",
+        "        transitive_sources = transitive_sources,",
+        "        uses_shared_libraries = uses_shared_libraries,",
+        "        has_py2_only_sources = has_py2_only_sources,",
+        "        has_py3_only_sources = has_py3_only_sources)",
+        "    return struct(py=info)",
+        "",
+        "userlib = rule(",
+        "    implementation = _userlib_impl,",
+        "    attrs = {",
+        "        'srcs': attr.label_list(allow_files=True),",
+        "        'deps': attr.label_list(providers=['py']),",
+        "        'uses_shared_libraries': attr.bool(),",
+        "        'has_py2_only_sources': attr.bool(),",
+        "        'has_py3_only_sources': attr.bool(),",
+        "    },",
+        ")");
+  }
+
+  @Test
+  public void librarySandwich() throws Exception {
+    // Use new version semantics so we don't validate source versions in py_library.
+    useConfiguration("--experimental_allow_python_version_transitions=true");
+    defineUserlibRule();
+    scratch.file(
+        "pkg/BUILD",
+        "load(':rules.bzl', 'userlib')",
+        "userlib(",
+        "    name = 'loweruserlib',",
+        "    srcs = ['loweruserlib.py'],",
+        "    uses_shared_libraries = True,",
+        "    has_py2_only_sources = True,",
+        ")",
+        "py_library(",
+        "    name = 'pylib',",
+        "    srcs = ['pylib.py'],",
+        "    deps = [':loweruserlib'],",
+        "    srcs_version = 'PY3ONLY'",
+        ")",
+        "userlib(",
+        "    name = 'upperuserlib',",
+        "    srcs = ['upperuserlib.py'],",
+        "    deps = [':pylib'],",
+        ")");
+    StructImpl info = PyProvider.getProvider(getConfiguredTarget("//pkg:upperuserlib"));
+    assertThat(PyProvider.getTransitiveSources(info))
+        .containsExactly(
+            getSourceArtifact("pkg/loweruserlib.py"),
+            getSourceArtifact("pkg/pylib.py"),
+            getSourceArtifact("pkg/upperuserlib.py"));
+    assertThat(PyProvider.getUsesSharedLibraries(info)).isTrue();
+    assertThat(PyProvider.getHasPy2OnlySources(info)).isTrue();
+    assertThat(PyProvider.getHasPy3OnlySources(info)).isTrue();
+  }
+}