fix(init): dedupe duplicate third-party provider names

Address GitHub Copilot review feedback on PR #1971: when two
distributions register a third-party provider under the same name in
the `commitizen.provider` entry-point group, the user previously saw
two ambiguous choices in `cz init`. Track names in a `seen_names`
set (seeded with the built-in names) and skip subsequent matches so
each name appears at most once.

The conflict is not silenced — `commitizen.providers.get_provider`
already raises `VersionProviderUnknown` if more than one entry point
shares the name, so the user gets a clear error if they pick the
duplicated provider, instead of a confusing UI showing two identical
choices that resolve the same way.

Add `test_construct_version_provider_choices_dedupes_duplicate_third_party`
which simulates two `EntryPoint(name="duplicated", ...)` values and
asserts only one appears in the choice list.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bearomorphism

commitizen/commands/init.py

@@ -83,6 +83,14 @@ def _construct_version_provider_choices() -> list[questionary.Choice]:
     third-party providers that register themselves under the
     `commitizen.provider` entry-point group. Third-party providers are
     not loaded — only their entry-point name is used for the choice.
+
+    Names already registered as built-ins are skipped to avoid showing
+    them twice (commitizen's own providers register under the same
+    entry-point group). When two distributions register a third-party
+    provider under the same name, the choice list deduplicates by name
+    so the user does not see ambiguous duplicate entries; the conflict
+    will surface with a clear error from `get_provider()` if the user
+    actually selects that name.
     """
     builtin_names = {
         option.provider_name for option in _BUILTIN_VERSION_PROVIDER_OPTIONS
@@ -91,14 +99,18 @@ def _construct_version_provider_choices() -> list[questionary.Choice]:
         questionary.Choice(title=option.title, value=option.provider_name)
         for option in _BUILTIN_VERSION_PROVIDER_OPTIONS
     ]
-    third_party_choices = [
-        questionary.Choice(
-            title=f"{ep.name}: third-party version provider",
-            value=ep.name,
+    third_party_choices: list[questionary.Choice] = []
+    seen_names: set[str] = set(builtin_names)
+    for ep in metadata.entry_points(group=PROVIDER_ENTRYPOINT):
+        if ep.name in seen_names:
+            continue
+        seen_names.add(ep.name)
+        third_party_choices.append(
+            questionary.Choice(
+                title=f"{ep.name}: third-party version provider",
+                value=ep.name,
+            )
         )
-        for ep in metadata.entry_points(group=PROVIDER_ENTRYPOINT)
-        if ep.name not in builtin_names
-    ]
     return [*builtin_choices, *third_party_choices]
 
 

tests/commands/test_init_command.py

@@ -551,3 +551,42 @@ def fake_entry_points(*args: Any, **kwargs: Any):
     # with the generic third-party suffix.
     assert values.count("pep621") == 1
     assert "pep621: third-party version provider" not in titles
+
+
+def test_construct_version_provider_choices_dedupes_duplicate_third_party(
+    mocker: MockFixture,
+):
+    """Two distributions registering the same provider name only show once."""
+    from commitizen.commands.init import _construct_version_provider_choices
+    from commitizen.providers import PROVIDER_ENTRYPOINT
+
+    real_entry_points = metadata.entry_points
+
+    duplicate_eps = [
+        metadata.EntryPoint(
+            name="duplicated",
+            value="dist_a.module:Provider",
+            group=PROVIDER_ENTRYPOINT,
+        ),
+        metadata.EntryPoint(
+            name="duplicated",
+            value="dist_b.module:Provider",
+            group=PROVIDER_ENTRYPOINT,
+        ),
+    ]
+
+    def fake_entry_points(*args: Any, **kwargs: Any):
+        eps = real_entry_points(*args, **kwargs)
+        if kwargs.get("group") == PROVIDER_ENTRYPOINT:
+            return list(eps) + duplicate_eps
+        return eps
+
+    mocker.patch(
+        "commitizen.commands.init.metadata.entry_points",
+        side_effect=fake_entry_points,
+    )
+
+    choices = _construct_version_provider_choices()
+    values = [choice.value for choice in choices]
+
+    assert values.count("duplicated") == 1