fix: validate default answer only after user input

copier/_main.py

@@ -607,6 +607,12 @@ def _ask(self) -> None:  # noqa: C901
                 raise CopierAnswersInterrupt(
                     self.answers, question, self.template
                 ) from err
+            # Computed values (i.e., `when: false`) are intentionally not
+            # validated at the moment.
+            # https://github.com/copier-org/copier/issues/1779#issuecomment-2365006990
+            # https://github.com/copier-org/copier/pull/1785
+            if question.get_when():
+                question.validate_answer(new_answer)
             self.answers.user[var_name] = new_answer
 
         # Reload external data, which may depend on answers

copier/_user_data.py

@@ -276,14 +276,7 @@ def get_default(self) -> Any:
                     result = self.render_value(
                         self.settings.defaults.get(self.var_name, self.default)
                     )
-        result = self.parse_answer(result)
-        # Computed values (i.e., `when: false`) are intentionally not validated
-        # at the moment.
-        # https://github.com/copier-org/copier/issues/1779#issuecomment-2365006990
-        # https://github.com/copier-org/copier/pull/1785
-        if self.get_when():
-            self.validate_answer(result)
-        return result
+        return self.parse_answer(result)
 
     def get_default_rendered(self) -> bool | str | Choice | None | MissingType:
         """Get default answer rendered for the questionary lib.

tests/test_prompt.py

@@ -451,6 +451,38 @@ def test_when(
     assert context == {"question_2": "something"}
 
 
+def test_default(tmp_path_factory: pytest.TempPathFactory, spawn: Spawn) -> None:
+    src, dst = map(tmp_path_factory.mktemp, ("src", "dst"))
+    build_file_tree(
+        {
+            (src / "copier.yml"): yaml.dump(
+                {
+                    "_envops": BRACKET_ENVOPS,
+                    "_templates_suffix": SUFFIX_TMPL,
+                    "team": {
+                        "type": "str",
+                        "default": "@copier-org/",
+                        "validator": "[% if not (team | regex_search('^@copier-org/.+$')) %]Must be a copier-org GitHub team[% endif %]",
+                    },
+                }
+            ),
+            (src / "[[ _copier_conf.answers_file ]].tmpl"): (
+                "[[ _copier_answers | to_nice_yaml ]]"
+            ),
+        }
+    )
+    tui = spawn(COPIER_PATH + ("copy", str(src), str(dst)))
+    expect_prompt(tui, "team", "str")
+    tui.expect_exact("@copier-org/")
+    tui.sendline("everyone")
+    tui.expect_exact(pexpect.EOF)
+    answers = load_answersfile_data(dst)
+    assert answers == {
+        "_src_path": str(src),
+        "team": "@copier-org/everyone",
+    }
+
+
 def test_placeholder(tmp_path_factory: pytest.TempPathFactory, spawn: Spawn) -> None:
     src, dst = map(tmp_path_factory.mktemp, ("src", "dst"))
     build_file_tree(