test: add test for get_match and wrong usages

part of #389

crates/pyo3/ast_grep_pyo3.pyi

@@ -1,4 +1,4 @@
-from typing import List, Optional, TypedDict, Unpack, Literal
+from typing import List, Optional, TypedDict, Unpack, Literal, overload
 
 class Pattern(TypedDict):
     selector: str
@@ -66,11 +66,18 @@ class SgNode:
     def follows(self, **rule: Unpack[Rule]) -> bool: ...
     def get_match(self, meta_var: str) -> Optional[SgNode]: ...
     def get_multiple_matches(self, meta_var: str) -> List[SgNode]: ...
+    def __getitem__(self, meta_var: str) -> SgNode: ...
 
     # Tree Traversal
     def get_root(self) -> SgRoot: ...
-    def find(self, config=None, **kwargs: Unpack[Rule]) -> SgNode: ...
-    def find_all(self, config=None, **kwargs: Unpack[Rule]) -> List[SgNode]: ...
+    @overload
+    def find(self, config=None) -> SgNode: ...
+    @overload
+    def find(self, **kwargs: Unpack[Rule]) -> SgNode: ...
+    @overload
+    def find_all(self, config=None) -> List[SgNode]: ...
+    @overload
+    def find_all(self, **kwargs: Unpack[Rule]) -> List[SgNode]: ...
     def field(self, name: str) -> Optional[SgNode]: ...
     def parent(self) -> Optional[SgNode]: ...
     def child(self, nth: int) -> Optional[SgNode]: ...

crates/pyo3/tests/test_simple.py

@@ -83,6 +83,15 @@ def test_get_match():
     assert rng.start.line == 1
     assert rng.start.column == 6
 
+def test_must_get_match():
+    node = root.find(pattern="let $A = $B")
+    a = node["A"]
+    assert a is not None
+    assert a.text() == "a"
+    rng = a.range()
+    assert rng.start.line == 1
+    assert rng.start.column == 6
+
 
 def test_get_multi_match():
     node = root.find(pattern="function test() { $$$STMT }")

crates/pyo3/tests/test_wrong_usage.py

@@ -0,0 +1,40 @@
+from ast_grep_pyo3 import SgRoot
+import pytest
+
+source = """
+function test() {
+  let a = 123
+  let b = 456
+  let c = 789
+}
+""".strip()
+sg = SgRoot(source, "javascript")
+root = sg.root()
+
+def test_wrong_use_pattern_as_dict():
+    with pytest.raises(TypeError):
+         root.find("let $A = 123")
+
+def test_get_unfound_match():
+    node = root.find(pattern="let $A = 123")
+    with pytest.raises(KeyError):
+        node["B"]
+
+# TODO: remove BaseException
+def test_wrong_rule_key():
+    with pytest.raises(BaseException):
+        root.find(pat="not") # type: ignore
+
+def test_no_rule_key():
+    with pytest.raises(BaseException):
+        root.find()
+
+def test_error_for_invalid_kind():
+    with pytest.raises(BaseException):
+        root.find(kind="nonsense")
+
+def test_no_error_for_invalid_pattern():
+    with pytest.raises(BaseException):
+        root.find(pattern="$@!!--l3**+no//nsense")
+    # but not this
+    assert not root.find(pattern="@test")