Fix version date calculation in corner cases (#149)

Previously, if the latest published stub version was higher
than the upstream version (which could happen with our old
versioning scheme), we always used the current date as
last component. This failed when uploading the same package
twice in a day – but also in our stub_uploader tests, which
simulate a new upload.

stub_uploader/get_version.py

@@ -50,8 +50,9 @@ def ensure_specificity(ver: list[int], specificity: int) -> None:
     ver.extend([0] * (specificity - len(ver)))
 
 
+# `today` can be passed as an argument for testing purposes.
 def compute_stub_version(
-    version_spec: Specifier, published_versions: list[Version], date: datetime.date
+    version_spec: Specifier, published_versions: list[Version], today: datetime.date
 ) -> Version:
     # The most important postcondition is that the incremented version is greater than
     # all published versions. This ensures that users who don't pin get the most
@@ -96,7 +97,8 @@ def compute_stub_version(
 
         # But can't keep versioning compatible with upstream...
         is_compatible = False
-        base_version_changed = True
+        # We also use the latest stub version as the base version, not the version_spec.
+        base_version_changed = False
 
     elif version_base.release > max_published.release[:specificity]:
         # For example, version_base=1.2, max_published=1.1.0.4, return 1.2.0.YYYYMMDD
@@ -111,7 +113,7 @@ def compute_stub_version(
         base_version_changed = False
 
     ensure_specificity(base_version_parts, stub_specificity)
-    unused_date = find_unused_date(max_published, base_version_changed, date)
+    unused_date = find_unused_date(max_published, base_version_changed, today)
     new_version_parts = [*base_version_parts[:-1], unused_date.strftime("%Y%m%d")]
     new_version = Version(".".join(map(str, new_version_parts)))
     assert_compatibility(
@@ -123,19 +125,25 @@ def compute_stub_version(
     return new_version
 
 
+# `today` can be passed as an argument for testing purposes.
 def find_unused_date(
-    max_published: Version, base_version_changed: bool, date: datetime.date
+    max_published: Version, base_version_changed: bool, today: datetime.date
 ) -> datetime.date:
+    # Is not necessarily a date in case the package predates the switch
+    # to the current versioning scheme.
+    last_date = max_published.release[-1]
+
     # If the base version changed, we should always be able to use the current date.
     if base_version_changed:
-        return date
+        return today
 
     # Make sure that the last published release is not unreasonable large.
-    assert int(date.strftime("%Y%m%d")) + 14 > max_published.release[-1]
+    assert int(today.strftime("%Y%m%d")) + 14 > last_date
 
-    while int(date.strftime("%Y%m%d")) <= max_published.release[-1]:
-        date = date + datetime.timedelta(days=1)
-    return date
+    new_date = today
+    while int(new_date.strftime("%Y%m%d")) <= last_date:
+        new_date += datetime.timedelta(days=1)
+    return new_date
 
 
 def assert_compatibility(

tests/test_unit.py

@@ -110,6 +110,7 @@ def test_compute_stub_version() -> None:
         _stub_ver("~=1.2.3", [f"1.2.3.{TODAY_V}", f"1.2.3.{TOMORROW_V}"])
         == f"1.2.3.{IN_TWO_DAYS_V}"
     )
+    assert _stub_ver("~=1.2.3", [f"1.4.0.{TODAY_V}"]) == f"1.4.0.{TOMORROW_V}"
 
 
 def test_collect_package_data() -> None: