fix: provide more clarification in unsafe error message (#1280)

Fixes #1269

Author: mitchnegus

copier/errors.py

@@ -106,7 +106,10 @@ class UnsafeTemplateError(CopierError):
     def __init__(self, features: Sequence[str]):
         assert features
         s = "s" if len(features) > 1 else ""
-        super().__init__(f"Template uses unsafe feature{s}: {', '.join(features)}")
+        super().__init__(
+            f"Template uses potentially unsafe feature{s}: {', '.join(features)}.\n"
+            "If you trust this template, consider adding the `--trust` option when running `copier copy/update`."
+        )
 
 
 # Warnings

tests/test_unsafe.py

@@ -33,7 +33,8 @@ class JinjaExtension(Extension):
         (
             {"_tasks": ["touch task.txt"]},
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: tasks"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: tasks.",
             ),
         ),
         (
@@ -60,7 +61,7 @@ class JinjaExtension(Extension):
             {"_jinja_extensions": ["tests.test_unsafe.JinjaExtension"]},
             pytest.raises(
                 UnsafeTemplateError,
-                match="Template uses unsafe feature: jinja_extensions",
+                match="Template uses potentially unsafe feature: jinja_extensions.",
             ),
         ),
         (
@@ -70,7 +71,7 @@ class JinjaExtension(Extension):
             },
             pytest.raises(
                 UnsafeTemplateError,
-                match="Template uses unsafe features: jinja_extensions, tasks",
+                match="Template uses potentially unsafe features: jinja_extensions, tasks.",
             ),
         ),
     ],
@@ -107,7 +108,7 @@ def test_copy_cli(
     else:
         assert retcode == 2
         _, err = capsys.readouterr()
-        assert "Template uses unsafe feature: tasks" in err
+        assert "Template uses potentially unsafe feature: tasks." in err
 
 
 @pytest.mark.parametrize(
@@ -127,21 +128,24 @@ def test_copy_cli(
             {"_tasks": ["touch task-old.txt"]},
             {},
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: tasks"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: tasks.",
             ),
         ),
         (
             {},
             {"_tasks": ["touch task-new.txt"]},
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: tasks"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: tasks.",
             ),
         ),
         (
             {"_tasks": ["touch task-old.txt"]},
             {"_tasks": ["touch task-new.txt"]},
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: tasks"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: tasks.",
             ),
         ),
         (
@@ -186,7 +190,8 @@ def test_copy_cli(
                 ]
             },
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: migrations"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: migrations.",
             ),
         ),
         (
@@ -200,7 +205,8 @@ def test_copy_cli(
                 ]
             },
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: migrations"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: migrations.",
             ),
         ),
         (
@@ -215,7 +221,8 @@ def test_copy_cli(
                 ]
             },
             pytest.raises(
-                UnsafeTemplateError, match="Template uses unsafe feature: migrations"
+                UnsafeTemplateError,
+                match="Template uses potentially unsafe feature: migrations.",
             ),
         ),
         (
@@ -228,23 +235,23 @@ def test_copy_cli(
             {},
             pytest.raises(
                 UnsafeTemplateError,
-                match="Template uses unsafe feature: jinja_extensions",
+                match="Template uses potentially unsafe feature: jinja_extensions.",
             ),
         ),
         (
             {},
             {"_jinja_extensions": ["tests.test_unsafe.JinjaExtension"]},
             pytest.raises(
                 UnsafeTemplateError,
-                match="Template uses unsafe feature: jinja_extensions",
+                match="Template uses potentially unsafe feature: jinja_extensions.",
             ),
         ),
         (
             {"_jinja_extensions": ["tests.test_unsafe.JinjaExtension"]},
             {"_jinja_extensions": ["tests.test_unsafe.JinjaExtension"]},
             pytest.raises(
                 UnsafeTemplateError,
-                match="Template uses unsafe feature: jinja_extensions",
+                match="Template uses potentially unsafe feature: jinja_extensions",
             ),
         ),
         (
@@ -263,8 +270,8 @@ def test_copy_cli(
             pytest.raises(
                 UnsafeTemplateError,
                 match=(
-                    "Template uses unsafe features: "
-                    "jinja_extensions, migrations, tasks"
+                    "Template uses potentially unsafe features: "
+                    "jinja_extensions, migrations, tasks."
                 ),
             ),
         ),
@@ -372,4 +379,4 @@ def test_update_cli(
     else:
         assert retcode == 2
         _, err = capsys.readouterr()
-        assert "Template uses unsafe feature: tasks" in err
+        assert "Template uses potentially unsafe feature: tasks." in err