[torch.package] add test case for repackaging parent module (pytorch#…

…72367)

Summary:
Pull Request resolved: pytorch#72367

Pull Request resolved: pytorch#72299

Test Plan:
Before pytorch#71520:
```
Summary
  Pass: 106
  Fail: 1
    ✗ caffe2/test:package - test_repackage_import_indirectly_via_parent_module (package.package_d.test_repackage.TestRepackage)
  Skip: 22
  ...
  ListingSuccess: 1
```

After pytorch#71520:

```
BUILD SUCCEEDED
    ✓ ListingSuccess: caffe2/test:package : 129 tests discovered (28.595)
    ✓ Pass: caffe2/test:package - test_repackage_import_indirectly_via_parent_module (package.package_d.test_repackage.TestRepackage) (18.635)
Summary
  Pass: 1
  ListingSuccess: 1
```

Reviewed By: PaliC

Differential Revision: D34015540

fbshipit-source-id: b45af5872ae4a5f52afbc0008494569d1080fa38
(cherry picked from commit 432d728)

test/package/package_d/imports_directly.py

@@ -0,0 +1,11 @@
+import torch
+
+from .subpackage_0.subsubpackage_0 import important_string
+
+
+class ImportsDirectlyFromSubSubPackage(torch.nn.Module):
+
+    key = important_string
+
+    def forward(self, inp):
+        return torch.sum(inp)

test/package/package_d/imports_indirectly.py

@@ -0,0 +1,11 @@
+import torch
+
+from .subpackage_0 import important_string
+
+
+class ImportsIndirectlyFromSubPackage(torch.nn.Module):
+
+    key = important_string
+
+    def forward(self, inp):
+        return torch.sum(inp)

test/package/package_d/subpackage_0/__init__.py

@@ -0,0 +1 @@
+from .subsubpackage_0 import important_string

test/package/package_d/subpackage_0/subsubpackage_0/__init__.py

@@ -0,0 +1 @@
+important_string = "subsubpackage_0"

test/package/test_repackage.py

@@ -0,0 +1,50 @@
+# Owner(s): ["oncall: package/deploy"]
+
+from io import BytesIO
+
+from torch.package import (
+    PackageExporter,
+    PackageImporter,
+    sys_importer,
+)
+from torch.testing._internal.common_utils import run_tests
+
+try:
+    from .common import PackageTestCase
+except ImportError:
+    # Support the case where we run this file directly.
+    from common import PackageTestCase
+
+
+class TestRepackage(PackageTestCase):
+    """Tests for repackaging."""
+
+    def test_repackage_import_indirectly_via_parent_module(self):
+        from package_d.imports_directly import ImportsDirectlyFromSubSubPackage
+        from package_d.imports_indirectly import ImportsIndirectlyFromSubPackage
+
+        model_a = ImportsDirectlyFromSubSubPackage()
+        buffer = BytesIO()
+        with PackageExporter(buffer) as pe:
+            pe.intern("**")
+            pe.save_pickle("default", "model.py", model_a)
+
+        buffer.seek(0)
+        pi = PackageImporter(buffer)
+        loaded_model = pi.load_pickle("default", "model.py")
+
+        model_b = ImportsIndirectlyFromSubPackage()
+        buffer = BytesIO()
+        with PackageExporter(
+            buffer,
+            importer=(
+                pi,
+                sys_importer,
+            ),
+        ) as pe:
+            pe.intern("**")
+            pe.save_pickle("default", "model_b.py", model_b)
+
+
+if __name__ == "__main__":
+    run_tests()