fuzz: Add option for more complete testing

Add a FUZZ_LEVEL environment variable that can be used to test the
language server features under the fuzzer in addition to the compiler.
It's not enabled by default, but can be useful to run locally.

tests/fuzz.py

@@ -7,25 +7,28 @@ from blueprintcompiler.outputs.xml import XmlOutput
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
 
-from blueprintcompiler import decompiler, gir, parser, tokenizer, utils
+from blueprintcompiler import gir, parser, tokenizer
 from blueprintcompiler.completions import complete
 from blueprintcompiler.errors import (
-    CompileError,
     CompilerBugError,
-    MultipleErrors,
     PrintableError,
 )
-from blueprintcompiler.tokenizer import Token, TokenType, tokenize
+from blueprintcompiler.lsp import LanguageServer
+
+fuzz_level = int(os.getenv("FUZZ_LEVEL") or "0")
 
 
 @PythonFuzz
-def fuzz(buf):
+def fuzz(buf: bytes):
     try:
         blueprint = buf.decode("ascii")
 
         tokens = tokenizer.tokenize(blueprint)
         ast, errors, warnings = parser.parse(tokens)
 
+        if fuzz_level >= 1:
+            assert_ast_doesnt_crash(blueprint, tokens, ast)
+
         xml = XmlOutput()
         if errors is None and ast is not None:
             xml.emit(ast)
@@ -37,6 +40,17 @@ def fuzz(buf):
         pass
 
 
+def assert_ast_doesnt_crash(text, tokens, ast):
+    lsp = LanguageServer()
+    for i in range(len(text) + 1):
+        ast.get_docs(i)
+    for i in range(len(text) + 1):
+        list(complete(lsp, ast, tokens, i))
+    for i in range(len(text) + 1):
+        ast.get_reference(i)
+    ast.get_document_symbols()
+
+
 if __name__ == "__main__":
     # Make sure Gtk 4.0 is accessible, otherwise every test will fail on that
     # and nothing interesting will be tested