tests(parser): add tests for annotation parser

tests/parser/test_annotation_parser.py

@@ -0,0 +1,130 @@
+from typing import Optional
+
+import pytest
+
+from core.ast.annotations import (
+    AnnotationStmt,
+    ConstraintExpr,
+    Expr,
+    LiteralExpr,
+    SchemaElementExpr,
+    SchemaExpr,
+    Stmt,
+    TypeExpr,
+    WildcardExpr,
+)
+from lexer.annotations import AnnotationLexer
+from lexer.position import Position
+from lexer.token import Token
+from parser.annotations import AnnotationParser
+
+
+class AstSerializer(Stmt.Visitor[str], Expr.Visitor[str]):
+    def serialize(self, stmt: Stmt):
+        return stmt.accept(self)
+
+    def visit_annotation_stmt(self, stmt: AnnotationStmt) -> str:
+        schema: str = ""
+        if stmt.schema is not None:
+            schema = " " + stmt.schema.accept(self)
+        return f"(annotation {stmt.name.lexeme}{schema})"
+
+    def visit_schema_expr(self, expr: SchemaExpr) -> str:
+        elements: list[str] = [elmt.accept(self) for elmt in expr.elements]
+        return f"(schema {' '.join(elements)})"
+
+    def visit_schema_element_expr(self, expr: SchemaElementExpr) -> str:
+        name: str = expr.name.lexeme if expr.name is not None else "_"
+        type: str = expr.type.accept(self) if expr.type is not None else "_"
+        return f"({name} {type})"
+
+    def visit_type_expr(self, expr: TypeExpr) -> str:
+        res: str = f"({expr.name.lexeme}"
+        for constraint in expr.constraints:
+            res += " " + constraint.accept(self)
+        res += ")"
+        return res
+
+    def visit_constraint_expr(self, expr: ConstraintExpr) -> str:
+        return f"(constraint {expr.left.accept(self)} {expr.op.lexeme} {expr.right.accept(self)})"
+
+    def visit_wildcard_expr(self, expr: WildcardExpr) -> str:
+        return "(_)"
+
+    def visit_literal_expr(self, expr: LiteralExpr) -> str:
+        return f"({expr.value})"
+
+
+def parse(source: str) -> Optional[Stmt]:
+    tokens: list[Token] = AnnotationLexer(source).process()
+    return AnnotationParser(tokens).parse()
+
+
+def must_parse(source: str) -> Stmt:
+    stmt: Optional[Stmt] = parse(source)
+    assert stmt is not None
+    return stmt
+
+
+def ast_str(source: str) -> str:
+    stmt: Stmt = must_parse(source)
+    return AstSerializer().serialize(stmt)
+
+
+@pytest.mark.parametrize(
+    "src,expected",
+    [
+        ("Type", "(annotation Type)"),
+        ("Type[]", "(annotation Type (schema ))"),
+        (
+            """
+            Frame[
+                verified: bool,
+                birth_year: int,
+                height: float + ( _ > 0 ) + ( _ < 250 ),
+                name: str,
+                date: datetime,
+                float,  # unnamed
+                unknown: _,  # untyped
+                _  # unnamed and untyped
+            ]
+            """,
+            "(annotation Frame (schema (verified (bool)) (birth_year (int)) (height (float (constraint (_) > (0.0)) (constraint (_) < (250.0)))) (name (str)) (date (datetime)) (_ (float)) (unknown _) (_ _)))",
+        ),
+    ],
+)
+def test_expressions(src: str, expected: str):
+    assert ast_str(src) == expected
+
+
+@pytest.mark.parametrize(
+    "src,pos,should_fail",
+    [
+        ("", (1, 1), True),
+        ("42", (1, 1), True),
+        ("True", (1, 1), True),
+        ("Type[", (1, 6), True),
+        ("Type[] Type2", (1, 8), False),
+        ("Type[bool:]", (1, 11), True),
+        ("Type[3]", (1, 6), True),
+        ("Type[bool float]", (1, 11), True),
+        ("Type[bool (_ < 2)]", (1, 11), True),
+        ("Type[bool + _ < 2)]", (1, 13), True),
+        ("Type[bool + (_ < 2]", (1, 19), True),
+        ("Type[bool + (< 2)]", (1, 14), True),
+        ("Type[bool + (_ + 2)]", (1, 16), True),
+        ("Type[bool + (Foo + Bar)]", (1, 14), True),
+        # ("Type[bool,]", (1, 11), True),  # trailing comma is accepted, TODO: update parser or EBNF
+        ("Type[bool, Type[]]", (1, 16), True),
+        ("Type[foo: 3]", (1, 11), True),
+    ],
+)
+def test_parsing_error(src: str, pos: tuple[int, int], should_fail: bool):
+    tokens: list[Token] = AnnotationLexer(src).process()
+    parser: AnnotationParser = AnnotationParser(tokens)
+    stmt: Optional[Stmt] = parser.parse()
+    if should_fail:
+        assert stmt is None
+    assert len(parser.errors) != 0
+    error_pos: Position = parser.errors[0].token.position
+    assert (error_pos.line, error_pos.column) == pos