recommend st.text(st.characters(codec)) for st.text(codec)

hypothesis-python/src/hypothesis/strategies/_internal/core.py

@@ -793,6 +793,19 @@ def text(
                 "The following elements in alphabet are not of length one, "
                 f"which leads to violation of size constraints:  {not_one_char!r}"
             )
+        if alphabet in {"ascii", "utf-8"}:
+            warnings.warn(
+                f"st.text({alphabet!r}): it seems like you are trying to use the "
+                f"codec {alphabet!r}. st.text({alphabet!r}) instead generates "
+                f"strings using the literal characters {list(alphabet)!r}. To specify "
+                f"the {alphabet} codec, use st.text(st.characters({alphabet!r})). "
+                "If you intended to use character literals, you can silence this "
+                "warning by reordering the characters.",
+                HypothesisWarning,
+                # this stacklevel is of course incorrect, but breaking out of the
+                # levels of LazyStrategy and validation isn't worthwhile.
+                stacklevel=1,
+            )
         char_strategy = (
             characters(categories=(), include_characters=alphabet)
             if alphabet

hypothesis-python/tests/cover/test_validation.py

@@ -9,11 +9,12 @@
 # obtain one at https://mozilla.org/MPL/2.0/.
 
 import functools
+import warnings
 
 import pytest
 
-from hypothesis import find, given
-from hypothesis.errors import InvalidArgument
+from hypothesis import find, given, strategies as st
+from hypothesis.errors import HypothesisWarning, InvalidArgument
 from hypothesis.internal.validation import check_type
 from hypothesis.strategies import (
     SearchStrategy as ActualSearchStrategy,
@@ -275,3 +276,27 @@ def test_check_strategy_might_suggest_sampled_from():
     with pytest.raises(InvalidArgument, match="such as st.sampled_from"):
         check_strategy_((1, 2, 3))
     check_strategy_(integers(), "passes for our custom coverage check")
+
+
+@pytest.mark.parametrize("codec", ["ascii", "utf-8"])
+def test_warn_on_strings_matching_common_codecs(codec):
+    with pytest.warns(
+        HypothesisWarning,
+        match=f"it seems like you are trying to use the codec {codec!r}",
+    ):
+
+        @given(st.text(codec))
+        def f(s):
+            pass
+
+        f()
+
+    # if we reorder, it doesn't warn anymore
+    with warnings.catch_warnings():
+        warnings.simplefilter("error")
+
+        @given(st.text(codec[1:] + codec[:1]))
+        def f(s):
+            pass
+
+        f()