[fine] Tests for type errors

WHEEEEEEE!

fine/build.rs

@@ -7,10 +7,8 @@ fn generate_test_for_file(path: PathBuf) -> String {
     let contents = fs::read_to_string(&path).expect("Unable to read input");
     let display_path = path.display().to_string();
 
-    let mut concrete_stuff: Option<String> = None;
-
     // Start iterating over lines and processing directives....
-    let mut type_assertions = Vec::new();
+    let mut assertions = Vec::new();
     let mut lines = contents.lines();
     while let Some(line) = lines.next() {
         let line = match line.strip_prefix("//") {
@@ -30,7 +28,10 @@ fn generate_test_for_file(path: PathBuf) -> String {
                 concrete.push_str(line);
                 concrete.push_str("\n");
             }
-            concrete_stuff = Some(concrete);
+
+            assertions.push(quote! {
+                crate::assert_concrete(&_tree, #concrete, #display_path);
+            });
         } else if let Some(line) = line.strip_prefix("type:") {
             let (pos, expected) = line
                 .trim()
@@ -41,26 +42,30 @@ fn generate_test_for_file(path: PathBuf) -> String {
                 .parse()
                 .expect(&format!("Unable to parse position '{pos}'"));
             let expected = expected.trim();
-            type_assertions.push(quote! {
+            assertions.push(quote! {
                 crate::assert_type_at(&_tree, &_lines, #pos, #expected, #display_path);
             });
+        } else if let Some(line) = line.strip_prefix("type-error:") {
+            let (pos, expected) = line
+                .trim()
+                .split_once(' ')
+                .expect("Mal-formed type-error expectation");
+            let pos: usize = pos
+                .trim()
+                .parse()
+                .expect(&format!("Unable to parse position '{pos}'"));
+            let expected = expected.trim();
+            assertions.push(quote! {
+                crate::assert_type_error_at(&_tree, &_lines, #pos, #expected, #display_path);
+            });
         }
     }
 
-    let concrete_comparison = if let Some(concrete) = concrete_stuff {
-        quote! {
-            crate::assert_concrete(&_tree, #concrete, #display_path)
-        }
-    } else {
-        quote! {}
-    };
-
     let name = format_ident!("{}", path.file_stem().unwrap().to_string_lossy());
     let test_method = quote! {
         fn #name() {
             let (_tree, _lines) = fine::parser::parse(#contents);
-            #concrete_comparison;
-            #(#type_assertions)*
+            #(#assertions)*
         }
     };
 

fine/src/semantics.rs

@@ -148,6 +148,10 @@ impl<'a> Semantics<'a> {
         semantics
     }
 
+    pub fn tree(&self) -> &SyntaxTree<'a> {
+        &self.syntax_tree
+    }
+
     pub fn snapshot_errors(&self) -> Vec<Error> {
         (*self.errors.borrow()).clone()
     }

fine/tests/example_tests.rs

@@ -85,6 +85,58 @@ fn assert_concrete(tree: &SyntaxTree, expected: &str, source_path: &str) {
     }
 }
 
+fn report_semantic_error(semantics: &Semantics, message: &str) {
+    let tree = semantics.tree();
+
+    println!("{message}! Parsed the tree as:");
+    println!("\n{}", tree.dump(true));
+
+    let errors = semantics.snapshot_errors();
+    if errors.len() == 0 {
+        println!("There were no errors reported during checking.\n");
+    } else {
+        println!(
+            "{} error{} reported during checking:",
+            errors.len(),
+            if errors.len() == 1 { "" } else { "s" }
+        );
+        for error in &errors {
+            println!("  Error: {error}");
+        }
+        println!();
+    }
+}
+
+macro_rules! semantic_panic {
+    ($semantics:expr, $($t:tt)*) => {{
+        let message = format!($($t)*);
+        report_semantic_error($semantics, &message);
+        panic!("{message}");
+    }};
+}
+
+macro_rules! semantic_assert {
+    ($semantics:expr, $pred:expr, $($t:tt)*) => {{
+        if !$pred {
+            let message = format!($($t)*);
+            report_semantic_error($semantics, &message);
+            panic!("{message}");
+        }
+    }};
+}
+
+macro_rules! semantic_assert_eq {
+    ($semantics:expr, $left:expr, $right:expr, $($t:tt)*) => {{
+        let ll = $left;
+        let rr = $right;
+        if ll != rr {
+            let message = format!($($t)*);
+            report_semantic_error($semantics, &message);
+            assert_eq!(ll, rr, "{}", message);
+        }
+    }};
+}
+
 fn assert_type_at(
     tree: &SyntaxTree,
     lines: &Lines,
@@ -92,46 +144,49 @@ fn assert_type_at(
     expected: &str,
     _source_path: &str,
 ) {
+    let semantics = Semantics::new(tree, lines);
     let tree_ref = match tree.find_tree_at(pos) {
         Some(t) => t,
-        None => {
-            println!("Unable to find the subtee at position {pos}! Parsed the tree as:");
-            println!("\n{}", tree.dump(true));
-            panic!("Cannot find tree at position {pos}");
-        }
+        None => semantic_panic!(&semantics, "Unable to find the subtee at position {pos}"),
     };
 
-    let semantics = Semantics::new(tree, lines);
     let tree_type = semantics.type_of(tree_ref, true);
-
     let actual = format!("{}", tree_type.unwrap_or(Type::Error));
-    if actual != expected {
-        println!(
-            "The type of the {:?} tree at position {pos} had the wrong type! Parsed the tree as:",
-            tree[tree_ref].kind
-        );
-        println!("\n{}", tree.dump(true));
+    semantic_assert_eq!(
+        &semantics,
+        expected,
+        actual,
+        "The type of the tree at position {pos} was incorrect"
+    );
+}
 
-        let errors = semantics.snapshot_errors();
-        if errors.len() == 0 {
-            println!("There were no errors reported during type checking.\n");
-        } else {
-            println!(
-                "{} error{} reported during type checking:",
-                errors.len(),
-                if errors.len() == 1 { "" } else { "s" }
-            );
-            for error in &errors {
-                println!("  Error: {error}");
-            }
-            println!();
-        }
+fn assert_type_error_at(
+    tree: &SyntaxTree,
+    lines: &Lines,
+    pos: usize,
+    expected: &str,
+    _source_path: &str,
+) {
+    let semantics = Semantics::new(tree, lines);
+    let tree_ref = match tree.find_tree_at(pos) {
+        Some(t) => t,
+        None => semantic_panic!(&semantics, "Unable to find the subtee at position {pos}"),
+    };
 
-        assert_eq!(
-            expected, actual,
-            "The type of the tree at position {pos} was incorrect"
-        );
-    }
+    let tree_type = semantics.type_of(tree_ref, true);
+    semantic_assert!(
+        &semantics,
+        matches!(tree_type, Some(Type::Error)),
+        "The type of the {:?} tree at position {pos} was '{tree_type:?}', not an error",
+        tree[tree_ref].kind
+    );
+
+    let errors = semantics.snapshot_errors();
+    semantic_assert!(
+        &semantics,
+        errors.iter().any(|e| e.message == expected),
+        "Unable to find the expected error message '{expected}'"
+    );
 }
 
 include!(concat!(env!("OUT_DIR"), "/generated_tests.rs"));

fine/tests/expression/errors/binary_mismatch.fine

@@ -0,0 +1,4 @@
+112 - "twenty five";
+"twenty five" - 112;
+// type-error: 4 cannot apply binary operator '-' to expressions of type 'f64' (on the left) and 'string' (on the right)
+// type-error: 35 cannot apply binary operator '-' to expressions of type 'string' (on the left) and 'f64' (on the right)

fine/tests/expression/errors/if_mismatched_arms.fine

@@ -0,0 +1,2 @@
+if true { "blarg" } else { 23 }
+// type-error: 0 the type of the `then` branch (string) must match the type of the `else` branch (f64)

fine/tests/expression/errors/if_not_bool.fine

@@ -0,0 +1,2 @@
+if 23 { "what" } else { "the" }
+// type-error: 0 conditions must yield a boolean

fine/tests/expression/errors/if_requires_else.fine

@@ -0,0 +1,2 @@
+if (if false { true }) { 32 } else { 23 }
+// type-error: 4 this conditional expression needs an else arm to produce a value

fine/tests/expression/errors/unary_mismatch.fine

@@ -0,0 +1,2 @@
+- "twenty five";
+// type-error: 0 cannot apply unary operator '-' to value of type string