feat(engine): route to_regex(engine=re|regex) through a backend layer; regex is a deferred-import extra

2 files changed, 83 insertions, 4 deletions

diff --git a/tests/builder/engine.test.py b/tests/builder/engine.test.py
index e569c71..c6a32d1 100644
--- a/tests/builder/engine.test.py
+++ b/tests/builder/engine.test.py
@@ -1,19 +1,53 @@
+import sys
+
 import pytest
 
 from edify import RegexBuilder
-from edify.errors.engine import EngineNotWiredError
+from edify.errors.backend import MissingRegexBackendError
 
 
 def test_engine_defaults_to_re_and_compiles():
     compiled = RegexBuilder().digit().to_regex()
     assert compiled.source == "\\d"
+    assert compiled.engine == "re"
 
 
-def test_engine_re_explicit_is_accepted():
+def test_engine_re_explicit_compiles_via_stdlib():
     compiled = RegexBuilder().digit().to_regex(engine="re")
     assert compiled.source == "\\d"
+    assert compiled.engine == "re"
+    assert compiled.compiled.__class__.__module__ == "re"
+
+
+def test_engine_regex_compiles_via_third_party_module():
+    compiled = RegexBuilder().digit().to_regex(engine="regex")
+    assert compiled.source == "\\d"
+    assert compiled.engine == "regex"
+    assert compiled.compiled.__class__.__module__.endswith("regex")
+
+
+def test_engine_regex_and_engine_re_are_not_equal_for_the_same_source():
+    left = RegexBuilder().digit().to_regex(engine="re")
+    right = RegexBuilder().digit().to_regex(engine="regex")
+    assert left != right
 
 
-def test_engine_regex_raises_until_wired():
-    with pytest.raises(EngineNotWiredError, match="engine='regex'"):
+def test_engine_regex_raises_clean_import_error_without_the_extra(monkeypatch):
+    monkeypatch.setitem(sys.modules, "regex", None)
+    with pytest.raises(MissingRegexBackendError, match="engine='regex'") as excinfo:
         RegexBuilder().digit().to_regex(engine="regex")
+    text = str(excinfo.value)
+    assert "pip install edify[regex]" in text
+    assert "= note:" in text
+
+
+def test_missing_regex_backend_error_chains_from_underlying_import_error(monkeypatch):
+    monkeypatch.setitem(sys.modules, "regex", None)
+    with pytest.raises(MissingRegexBackendError) as excinfo:
+        RegexBuilder().digit().to_regex(engine="regex")
+    assert isinstance(excinfo.value.__cause__, ImportError)
+
+
+def test_regex_engine_flags_propagate():
+    compiled = RegexBuilder().string("ABC").to_regex(engine="regex", ignore_case=True)
+    assert bool(compiled.search("abc"))
diff --git a/tests/builder/flags.test.py b/tests/builder/flags.test.py
index d35d2ff..02e875e 100644
--- a/tests/builder/flags.test.py
+++ b/tests/builder/flags.test.py
@@ -70,3 +70,48 @@ def test_multiple_kwargs_combine():
     assert compiled.compiled.flags & re.I == re.I
     assert compiled.compiled.flags & re.M == re.M
     assert compiled.compiled.flags & re.S == re.S
+
+
+def _regex_module():
+    import regex
+
+    return regex
+
+
+def test_regex_engine_ignore_case_kwarg_enables_the_flag():
+    regex = _regex_module()
+    compiled = RegexBuilder().string("hi").to_regex(engine="regex", ignore_case=True)
+    assert compiled.compiled.flags & regex.I == regex.I
+
+
+def test_regex_engine_multiline_kwarg_enables_the_flag():
+    regex = _regex_module()
+    compiled = RegexBuilder().string("hi").to_regex(engine="regex", multiline=True)
+    assert compiled.compiled.flags & regex.M == regex.M
+
+
+def test_regex_engine_dotall_kwarg_enables_the_flag():
+    regex = _regex_module()
+    compiled = RegexBuilder().string("hi").to_regex(engine="regex", dotall=True)
+    assert compiled.compiled.flags & regex.S == regex.S
+
+
+def test_regex_engine_ascii_only_kwarg_enables_the_flag():
+    regex = _regex_module()
+    compiled = RegexBuilder().string("hi").to_regex(engine="regex", ascii_only=True)
+    assert compiled.compiled.flags & regex.A == regex.A
+
+
+def test_regex_engine_verbose_kwarg_enables_the_flag():
+    regex = _regex_module()
+    compiled = RegexBuilder().string("hi").to_regex(engine="regex", verbose=True)
+    assert compiled.compiled.flags & regex.X == regex.X
+
+
[email protected](
+    _ON_PYPY,
+    reason="PyPy's regex.DEBUG opcode disassembler shares the same upstream disassembler bug",
+)
+def test_regex_engine_debug_kwarg_compiles_without_error():
+    compiled = RegexBuilder().string("hi").to_regex(engine="regex", debug=True)
+    assert compiled.source == "hi"