Handle Cairo 1 print (#1803)

Cairo PR: software-mansion-labs/cairo#65

protostar/cairo_testing/cairo_hint_local_factory.py

@@ -22,6 +22,7 @@
     MockCallHintLocal,
     ExpectCallHintLocal,
     AssertExpectCallHintLocal,
+    PrintHintLocal,
 )
 from protostar.cheatable_starknet.callable_hint_locals.stop_prank_hint_local import (
     StopPrankHintLocal,
@@ -116,6 +117,7 @@ def build_hint_locals(self) -> List[HintLocal]:
             MockCallHintLocal(controller=contracts_controller),
             ExpectCallHintLocal(controller=expect_call_controller),
             AssertExpectCallHintLocal(controller=expect_call_controller),
+            PrintHintLocal(),
         ]
 
 

protostar/cheatable_starknet/callable_hint_locals/__init__.py

@@ -16,3 +16,4 @@
 from .mock_call_hint_local import MockCallHintLocal
 from .expect_call_hint_local import ExpectCallHintLocal
 from .assert_expect_call_hint_local import AssertExpectCallHintLocal
+from .print_hint_local import PrintHintLocal

protostar/cheatable_starknet/callable_hint_locals/print_hint_local.py

@@ -0,0 +1,20 @@
+from typing import Callable
+
+from protostar.cheatable_starknet.controllers.io import protostar_print
+from protostar.starknet.data_transformer import CairoData
+
+from .callable_hint_local import CallableHintLocal
+
+
+class PrintHintLocal(CallableHintLocal):
+    @property
+    def name(self) -> str:
+        return "protostar_print"
+
+    def _build(
+        self,
+    ) -> Callable[[CairoData], None]:
+        return self.protostar_print
+
+    def protostar_print(self, data: CairoData) -> None:
+        protostar_print(data=data)

protostar/cheatable_starknet/controllers/io.py

@@ -0,0 +1,10 @@
+from protostar.starknet.data_transformer import CairoData
+from protostar.cairo.short_string import short_string_to_str
+
+
+def protostar_print(data: CairoData):
+    for data_item in data:
+        str_data = short_string_to_str(data_item)
+        original_value_msg = f"original value: [{str(data_item)}]"
+        converted_value_msg = f"converted to a string: [{str_data}]"
+        print(original_value_msg, converted_value_msg)

tests/integration/cairo1/compiler_bindings/test_print.py

@@ -0,0 +1,48 @@
+from pathlib import Path
+
+import pytest
+
+from tests.integration._conftest import ProtostarProjectFixture
+from tests.integration.conftest import (
+    CreateProtostarProjectFixture,
+    assert_cairo_test_cases,
+)
+from protostar.testing.test_results import PassedTestCaseResult
+
+
+@pytest.fixture(name="protostar_project", scope="function")
+def protostar_fixture(create_protostar_project: CreateProtostarProjectFixture):
+    with create_protostar_project() as protostar_project:
+        yield protostar_project
+
+
+async def test_print(protostar_project: ProtostarProjectFixture, datadir: Path):
+    testing_summary = await protostar_project.protostar.test_cairo1(
+        datadir / "print_test.cairo",
+    )
+
+    assert_cairo_test_cases(
+        testing_summary,
+        expected_passed_test_cases_names=["test_print_basic"],
+    )
+
+    expected_outputs = {
+        "test_print_basic": [
+            "original value: [448378203247] converted to a string: [hello]",
+            "original value: [1953658213] converted to a string: [true]",
+            "original value: [439721161573] converted to a string: [false]",
+            "original value: [1953658213] converted to a string: [true]",
+            "original value: [1986358889] converted to a string: [veni]",
+            "original value: [1986618473] converted to a string: [vidi]",
+            "original value: [1986618217] converted to a string: [vici]",
+        ],
+    }
+
+    mapping_item = testing_summary.test_suites_mapping.get(datadir / "print_test.cairo")
+    assert mapping_item is not None
+
+    for item in mapping_item:
+        assert isinstance(item, PassedTestCaseResult)
+        expected_outputs_list = expected_outputs[item.test_case_name]
+        for expected_output in expected_outputs_list:
+            assert expected_output in item.captured_stdout["test"]

tests/integration/cairo1/compiler_bindings/test_print/print_test.cairo

@@ -0,0 +1,22 @@
+use array::ArrayTrait;
+use protostar_print::PrintTrait;
+use result::ResultTrait;
+
+#[test]
+fn test_print_basic() {
+  1.print();
+
+  'hello'.print();
+
+  let mut array = ArrayTrait::new();
+  array.append('veni');
+  array.append('vidi');
+  array.append('vici');
+  array.print();
+
+  (1 == 2).print();
+
+  true.print();
+
+  assert(1 == 1, 'xxx');
+}

website/docs/tutorials/08-cairo-1-support/07-debugging.md

@@ -0,0 +1,36 @@
+---
+sidebar_label: Debugging
+---
+
+Currently, Cairo does not support a debugging mechanism per se, but we can print variables' values to the standard output.
+
+# Printing to stdout
+
+In order to print a variable's value to the standard output, we have to use `PrintTrait`:
+
+```
+use array::ArrayTrait;
+use protostar_print::PrintTrait;
+use result::ResultTrait;
+
+#[test]
+fn test_print_basic() {
+  1.print();
+
+  'hello'.print();
+
+  let mut array = ArrayTrait::new();
+  array.append('veni');
+  array.append('vidi');
+  array.append('vici');
+  array.print();
+
+  (1 == 2).print();
+
+  true.print();
+
+  assert(1 == 1, 'xxx');
+}
+```
+
+You can print numbers, booleans and [Cairo short strings](https://www.cairo-lang.org/docs/how_cairo_works/consts.html#short-string-literals) as well as arrays containing values of these types.