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/kcl/src/ast/types.rs

@@ -2862,7 +2862,7 @@ impl MemberExpression {
                     // Actually evaluate memory to compute the property.
                     let prop = memory.get(&name, property_src)?;
                     let MemoryItem::UserVal(prop) = prop else {
-                        return Err(KclError::Syntax(KclErrorDetails {
+                        return Err(KclError::Semantic(KclErrorDetails {
                             source_ranges: property_sr,
                             message: format!(
                                 "{name} is not a valid property/index, you can only use a string or int (>= 0) here",
@@ -2876,17 +2876,17 @@ impl MemberExpression {
                                 .and_then(|x| usize::try_from(x).ok())
                                 .map(Property::Number)
                                 .ok_or_else(|| {
-                                    KclError::Syntax(KclErrorDetails {
+                                    KclError::Semantic(KclErrorDetails {
                                         source_ranges: property_sr,
                                         message: format!(
-                                            "{name} is not a valid property/index, you can only use a string or int (>= 0) here",
+                                            "{name}'s value is not a valid property/index, you can only use a string or int (>= 0) here",
                                         ),
                                     })
                                 })?
                         }
                         JValue::String(ref x) => Property::String(x.to_owned()),
                         _ => {
-                            return Err(KclError::Syntax(KclErrorDetails {
+                            return Err(KclError::Semantic(KclErrorDetails {
                                 source_ranges: property_sr,
                                 message: format!(
                                     "{name} is not a valid property/index, you can only use a string to get the property of an object, or an int (>= 0) to get an item in an array",
@@ -2903,7 +2903,7 @@ impl MemberExpression {
                         if let Ok(x) = u64::try_from(x) {
                             Property::Number(x.try_into().unwrap())
                         } else {
-                            return Err(KclError::Syntax(KclErrorDetails {
+                            return Err(KclError::Semantic(KclErrorDetails {
                                 source_ranges: property_sr,
                                 message: format!("{x} is not a valid index, indices must be whole numbers >= 0"),
                             }));
@@ -2911,7 +2911,7 @@ impl MemberExpression {
                     }
                     LiteralValue::String(s) => Property::String(s),
                     _ => {
-                        return Err(KclError::Syntax(KclErrorDetails {
+                        return Err(KclError::Semantic(KclErrorDetails {
                             source_ranges: vec![self.into()],
                             message: "Only strings or ints (>= 0) can be properties/indexes".to_owned(),
                         }));
@@ -2943,7 +2943,7 @@ impl MemberExpression {
                     }))
                 } else {
                     Err(KclError::UndefinedValue(KclErrorDetails {
-                        message: format!("Property {property} not found in object"),
+                        message: format!("Property '{property}' not found in object"),
                         source_ranges: vec![self.clone().into()],
                     }))
                 }
@@ -2978,10 +2978,13 @@ impl MemberExpression {
                 ),
                 source_ranges: vec![self.clone().into()],
             })),
-            (_, _) => Err(KclError::Semantic(KclErrorDetails {
+            (being_indexed, _) => {
-                message: "Only arrays and objects can be indexed".to_owned(),
+                let t = human_friendly_type(being_indexed);
-                source_ranges: vec![self.clone().into()],
+                Err(KclError::Semantic(KclErrorDetails {
-            })),
+                    message: format!("Only arrays and objects can be indexed, but you're trying to index a {t}"),
+                    source_ranges: vec![self.clone().into()],
+                }))
+            }
         }
     }
 
@@ -4070,6 +4073,17 @@ impl ConstraintLevels {
     }
 }
 
+fn human_friendly_type(j: JValue) -> &'static str {
+    match j {
+        JValue::Null => "null",
+        JValue::Bool(_) => "boolean (true/false value)",
+        JValue::Number(_) => "number",
+        JValue::String(_) => "string (text)",
+        JValue::Array(_) => "array (list)",
+        JValue::Object(_) => "object",
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use pretty_assertions::assert_eq;

src/wasm-lib/tests/executor/inputs/no_visuals/array_index_oob.kcl

@@ -0,0 +1,2 @@
+let arr = []
+let x = arr[0]

src/wasm-lib/tests/executor/inputs/no_visuals/index_of_array.kcl

@@ -0,0 +1,18 @@
+// This tests indexing an array.
+
+const array = [90, 91, 92]
+
+// Test: literal index.
+
+const result0 = array[1]
+
+assertLessThanOrEq(result0, 91, "Literal property lookup")
+assertGreaterThanOrEq(result0, 91, "Literal property lookup")
+
+// Test: computed index.
+
+const i = int(1 + 0)
+const result1 = array[i]
+
+assertLessThanOrEq(result1, 91, "Computed property lookup")
+assertGreaterThanOrEq(result1, 91, "Computed property lookup")

src/wasm-lib/tests/executor/inputs/no_visuals/invalid_index_fractional.kcl

@@ -0,0 +1,2 @@
+let arr = [1, 2, 3]
+let x = arr[1.2]

src/wasm-lib/tests/executor/inputs/no_visuals/invalid_index_negative.kcl

@@ -0,0 +1,3 @@
+let arr = [1, 2, 3]
+let i = -1
+let x = arr[i]

src/wasm-lib/tests/executor/inputs/no_visuals/invalid_index_str.kcl

@@ -0,0 +1,2 @@
+let arr = [1, 2, 3]
+let x = arr["s"]

src/wasm-lib/tests/executor/inputs/no_visuals/invalid_member_object.kcl

@@ -0,0 +1,2 @@
+let num = 999
+let x = num[3]

src/wasm-lib/tests/executor/inputs/no_visuals/invalid_member_object_prop.kcl

@@ -0,0 +1,2 @@
+let b = true
+let x = b["property"]

src/wasm-lib/tests/executor/inputs/no_visuals/non_string_key_of_object.kcl

@@ -0,0 +1,2 @@
+let obj = {key: 123}
+let num = obj[3]

src/wasm-lib/tests/executor/inputs/no_visuals/object_prop_not_found.kcl

@@ -0,0 +1,2 @@
+let obj = {}
+let k = obj["age"]

src/wasm-lib/tests/executor/inputs/no_visuals/property_of_object.kcl

@@ -0,0 +1,40 @@
+// This tests evaluating properties of objects.
+
+const obj = {
+  foo: 1,
+  bar: 0,
+}
+
+// Test: the property is a literal.
+
+const one_a = obj["foo"]
+
+assertLessThanOrEq(one_a,    1, "Literal property lookup")
+assertGreaterThanOrEq(one_a, 1, "Literal property lookup")
+
+// Test: the property is a variable,
+// which must be evaluated before looking it up.
+
+const p = "foo"
+const one_b = obj[p]
+
+assertLessThanOrEq(one_b,    1, "Computed property lookup")
+assertGreaterThanOrEq(one_b, 1, "Computed property lookup")
+
+// Test: multiple literal properties.
+
+const obj2 = {
+  inner: obj,
+}
+
+const one_c = obj2.inner["foo"]
+
+assertLessThanOrEq(one_c,    1, "Literal property lookup")
+assertGreaterThanOrEq(one_c, 1, "Literal property lookup")
+
+// Test: multiple properties, mix of literal and computed.
+
+const one_d = obj2.inner[p]
+
+assertLessThanOrEq(one_d,    1, "Computed property lookup")
+assertGreaterThanOrEq(one_d, 1, "Computed property lookup")

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

@@ -4,7 +4,7 @@ use kcl_lib::{settings::types::UnitLength, test_server::execute_and_snapshot};
 /// i.e. how different the current model snapshot can be from the previous saved one.
 const MIN_DIFF: f64 = 0.99;
 
-// mod server;
+mod no_visuals;
 
 macro_rules! kcl_input {
     ($file:literal) => {

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"
+);