Initial commit

tests/hypot.py

@@ -0,0 +1,70 @@
+"""Reusable hypothesis strategies for CSS selectors."""
+
+from typing import cast
+
+from hypothesis import strategies as st
+
+# CSS identifier (used for tag, class, ID names)
+css_ident = st.from_regex(r"[_a-zA-Z][_a-zA-Z0-9-]*", fullmatch=True)
+
+css_tag = css_ident
+css_class = css_ident.map(lambda x: f".{x}")
+css_class_multi = st.lists(css_class, min_size=1).map("".join)
+css_id = css_ident.map(lambda x: f"#{x}")
+
+# Any amount of whitespace, including none (spaces only)
+_whitespace = st.from_regex(r" *", fullmatch=True)
+
+
+def simple_selector() -> st.SearchStrategy[str]:
+    """Returns a strategy for simple seletors: tag, .class, #id (all optional, at least one)."""
+
+    # Optional tag + (one or more classes) + optional id, at least one item present
+    parts = st.tuples(
+        st.none() | css_tag,
+        st.none() | css_class_multi,
+        st.none() | css_id,
+    ).filter(lambda parts: any(parts))
+
+    return parts.map(lambda parts: "".join(p for p in parts if p))
+
+
+# nth-child pseudo-classes
+nth_child_suffix = st.from_regex(r":nth-child\([1-9][0-9]*\)", fullmatch=True)
+_specific_child_pseudo_classes = st.sampled_from([":first-child", ":last-child"])
+any_nth_child_suffix = st.one_of(nth_child_suffix, _specific_child_pseudo_classes)
+
+
+def not_selector(inner: st.SearchStrategy[str]) -> st.SearchStrategy[str]:
+    return st.tuples(st.just(":not("), _whitespace, inner, _whitespace, st.just(")")).map("".join)
+
+
+def pseudo_suffixes(inner: st.SearchStrategy[str]) -> st.SearchStrategy[str]:
+    """Generate a single random pseudo-class suffix."""
+    return st.one_of(
+        not_selector(inner),
+        any_nth_child_suffix,
+    )
+
+
+combinator = st.tuples(_whitespace, st.sampled_from([">", " ", "+", ",", "~"]), _whitespace).map("".join)
+
+selector = st.recursive(
+    # Base: simple selector + pseudo-classes
+    base=simple_selector(),
+    extend=lambda s: st.one_of(
+        # Add combinator + selector sequence
+        cast(
+            "st.SearchStrategy[str]",
+            st.builds(
+                lambda left, comb, right: left + comb + right,
+                s,
+                combinator,
+                s,
+            ),
+        ),
+        # Apply pseudo-suffix
+        st.tuples(s, pseudo_suffixes(s)).map("".join),
+    ),
+    max_leaves=10,
+)