fix(unit): preserve fuzzy state for formats without fuzzy support (#18421)

Consider the following: There is an **untranslated** unit in a file format that doesn't support
writing fuzzy state to the file. The project has been configured with approved only commit
policy. The unit is translated to a fuzzy state. As it is the first uncommitted change to
the unit, `unit.details["disk_state"]["state"]"` will be updated and set to `STATE_EMPTY`.
`unit.state` is `STATE_FUZZY`. There is a `PendingUnitChange` in the database to commit the
translation to disk.

When a file sync is triggered, it attempts a commit. The pending change above is not committed
because it is not approved and nothing changes so far. During file sync, `Unit.update_from_unit`
is called on this unit which in turn calls `Unit.get_unit_state` to get current unit state.
`unit.state` is `STATE_FUZZY` so `unit.is_fuzzy(fallback=True)` is called.

https://github.com/WeblateOrg/weblate/blob/370adc360759d3453598eb0b3b4074539093456a/weblate/trans/models/unit.py#L857-L858

JSON format is not `SUPPORTS_FUZZY` so the fallback is returned directly.

https://github.com/WeblateOrg/weblate/blob/370adc360759d3453598eb0b3b4074539093456a/weblate/formats/ttkit.py#L158-L166

As a result, `Unit.get_unit_state` returns `STATE_FUZZY`. `comparison_state["state"]` is STATE_EMPTY.
`same_state` evaluates to `False` and the pending change is deleted from the database.

https://github.com/WeblateOrg/weblate/blob/370adc360759d3453598eb0b3b4074539093456a/weblate/trans/models/unit.py#L1102

* check whether unit is empty in `is_fuzzy`

Author: amCap1712

weblate/formats/ttkit.py

@@ -159,10 +159,12 @@ def is_fuzzy(self, fallback=False):
         """Check whether unit needs editing."""
         if not self.has_unit():
             return fallback
+        if not self.has_translation():
+            return False
         # Most of the formats do not support this, but they
         # happily return False
         if isinstance(self.unit, SUPPORTS_FUZZY):
-            return self.has_translation() and self.unit.isfuzzy()
+            return self.unit.isfuzzy()
         return fallback
 
     def has_content(self) -> bool:

weblate/trans/tests/test_remote.py

@@ -16,7 +16,12 @@
 from weblate.trans.tests.test_views import ViewTestCase
 from weblate.trans.tests.utils import REPOWEB_URL
 from weblate.utils.files import remove_tree
-from weblate.utils.state import STATE_APPROVED, STATE_EMPTY, STATE_TRANSLATED
+from weblate.utils.state import (
+    STATE_APPROVED,
+    STATE_EMPTY,
+    STATE_FUZZY,
+    STATE_TRANSLATED,
+)
 from weblate.vcs.models import VCS_REGISTRY
 
 EXTRA_PO = """
@@ -809,6 +814,41 @@ def test_tbx_explanation_sync(self) -> None:
 
         self.assertEqual(PendingUnitChange.objects.filter(unit=unit).count(), 0)
 
+    def _test_fuzzy_state_commit_policy(self, component) -> None:
+        self.project.commit_policy = CommitPolicyChoices.APPROVED_ONLY
+        self.project.translation_review = True
+        self.project.save()
+
+        translation = component.translation_set.get(language_code="cs")
+        unit = translation.unit_set.get(source="Hello, world!\n")
+
+        unit.translate(self.user, "Ahoj světe!\n", STATE_FUZZY)
+        self.assertEqual(unit.state, STATE_FUZZY)
+        self.assertEqual(unit.details["disk_state"]["state"], STATE_EMPTY)
+
+        count = PendingUnitChange.objects.filter(unit=unit).count()
+        self.assertEqual(count, 1)
+
+        # trigger commit and check_sync to simulate repository rescan
+        translation.commit_pending("test", None)
+        translation.check_sync(force=True)
+
+        unit = translation.unit_set.get(source="Hello, world!\n")
+        self.assertEqual(unit.state, STATE_FUZZY)
+
+        # pending changes for unit are not discarded
+        count = PendingUnitChange.objects.filter(unit=unit).count()
+        self.assertEqual(count, 1)
+        self.assertEqual(unit.details["disk_state"]["state"], STATE_EMPTY)
+
+    def test_fuzzy_state_commit_policy_json(self) -> None:
+        component = self.create_json(name="JSON component", project=self.project)
+        self._test_fuzzy_state_commit_policy(component)
+
+    def test_fuzzy_state_commit_policy_po(self) -> None:
+        component = self.create_po(name="Po component", project=self.project)
+        self._test_fuzzy_state_commit_policy(component)
+
 
 class GitBranchMultiRepoTest(MultiRepoTest):
     _vcs = "git"

weblate/trans/tests/utils.py

@@ -336,8 +336,8 @@ def create_android(self, suffix="", **kwargs) -> Component:
             **kwargs,
         )
 
-    def create_json(self) -> Component:
-        return self._create_component("json", "json/*.json")
+    def create_json(self, **kwargs) -> Component:
+        return self._create_component("json", "json/*.json", **kwargs)
 
     def create_json_mono(self, suffix="mono", **kwargs) -> Component:
         return self._create_component(