Easy KCL tests with no engine/visuals (#3282)

This new test framework, `no_visuals`, is for testing KCL programs via asserts, not via twenty-twenty visual tests. This is useful for unit-testing small fragments of KCL.

It's easy! All you need to do is:
- Write a KCL file
- Save it under `tests/executor/inputs/no_visuals/foo.kcl`
- Open `no_visuals.rs` and add `gen_test!(foo);`

src/wasm-lib/tests/executor/no_visuals.rs

@@ -0,0 +1,87 @@
+use kcl_lib::{ast::types::Program, errors::KclError, executor::ExecutorContext};
+
+macro_rules! gen_test {
+    ($file:ident) => {
+        #[tokio::test]
+        async fn $file() {
+            let code = include_str!(concat!("inputs/no_visuals/", stringify!($file), ".kcl"));
+            run(&code).await;
+        }
+    };
+}
+
+macro_rules! gen_test_fail {
+    ($file:ident, $expected:literal) => {
+        #[tokio::test]
+        async fn $file() {
+            let code = include_str!(concat!("inputs/no_visuals/", stringify!($file), ".kcl"));
+            let actual = run_fail(&code).await;
+            assert_eq!(actual.get_message(), $expected);
+        }
+    };
+}
+
+async fn run(code: &str) {
+    let (ctx, program) = setup(code).await;
+
+    ctx.run(&program, None).await.unwrap();
+}
+
+async fn setup(program: &str) -> (ExecutorContext, Program) {
+    let tokens = kcl_lib::token::lexer(program).unwrap();
+    let parser = kcl_lib::parser::Parser::new(tokens);
+    let program = parser.ast().unwrap();
+    let ctx = kcl_lib::executor::ExecutorContext {
+        engine: std::sync::Arc::new(Box::new(
+            kcl_lib::engine::conn_mock::EngineConnection::new().await.unwrap(),
+        )),
+        fs: std::sync::Arc::new(kcl_lib::fs::FileManager::new()),
+        stdlib: std::sync::Arc::new(kcl_lib::std::StdLib::new()),
+        settings: Default::default(),
+        is_mock: true,
+    };
+    (ctx, program)
+}
+
+async fn run_fail(code: &str) -> KclError {
+    let (ctx, program) = setup(code).await;
+    let Err(e) = ctx.run(&program, None).await else {
+        panic!("Expected this KCL program to fail, but it (incorrectly) never threw an error.");
+    };
+    e
+}
+
+gen_test!(property_of_object);
+gen_test!(index_of_array);
+gen_test_fail!(
+    invalid_index_str,
+    "semantic: Only integers >= 0 can be used as the index of an array, but you're using a string"
+);
+gen_test_fail!(
+    invalid_index_negative,
+    "semantic: i's value is not a valid property/index, you can only use a string or int (>= 0) here"
+);
+gen_test_fail!(
+    invalid_index_fractional,
+    "semantic: Only strings or ints (>= 0) can be properties/indexes"
+);
+gen_test_fail!(
+    invalid_member_object,
+    "semantic: Only arrays and objects can be indexed, but you're trying to index a number"
+);
+gen_test_fail!(
+    invalid_member_object_prop,
+    "semantic: Only arrays and objects can be indexed, but you're trying to index a boolean (true/false value)"
+);
+gen_test_fail!(
+    non_string_key_of_object,
+    "semantic: Only strings can be used as the property of an object, but you're using a number"
+);
+gen_test_fail!(
+    array_index_oob,
+    "undefined value: The array doesn't have any item at index 0"
+);
+gen_test_fail!(
+    object_prop_not_found,
+    "undefined value: Property 'age' not found in object"
+);