Collect and display evaluation hints on test failures.

crates/lang/src/ast.rs

@@ -85,6 +85,21 @@ pub struct Function<T, Expr> {
 pub type TypedTypeAlias = TypeAlias<Arc<Type>>;
 pub type UntypedTypeAlias = TypeAlias<()>;
 
+impl TypedFunction {
+    pub fn test_hint(&self) -> Option<(BinOp, Box<TypedExpr>, Box<TypedExpr>)> {
+        match &self.body {
+            TypedExpr::BinOp {
+                name,
+                tipo,
+                left,
+                right,
+                ..
+            } if tipo == &bool() => Some((name.clone(), left.clone(), right.clone())),
+            _ => None,
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct TypeAlias<T> {
     pub alias: String,

crates/project/src/error.rs

@@ -1,13 +1,18 @@
+use crate::{pretty, script::EvalHint};
+use aiken_lang::{
+    ast::{BinOp, Span},
+    parser::error::ParseError,
+    tipo,
+};
+use miette::{
+    Diagnostic, EyreContext, LabeledSpan, MietteHandlerOpts, NamedSource, RgbColors, SourceCode,
+};
 use std::{
     fmt::{Debug, Display},
     io,
     path::{Path, PathBuf},
 };
-
+use uplc::machine::cost_model::ExBudget;
-use aiken_lang::{ast::Span, parser::error::ParseError, tipo};
-use miette::{
-    Diagnostic, EyreContext, LabeledSpan, MietteHandlerOpts, NamedSource, RgbColors, SourceCode,
-};
 
 #[allow(dead_code)]
 #[derive(thiserror::Error)]
@@ -75,7 +80,11 @@ pub enum Error {
     },
 
     #[error("{} failed", name)]
-    TestFailure { name: String, path: PathBuf },
+    TestFailure {
+        name: String,
+        path: PathBuf,
+        evaluation_hint: Option<EvalHint>,
+    },
 }
 
 impl Error {
@@ -231,7 +240,34 @@ impl Diagnostic for Error {
             Error::Format { .. } => None,
             Error::ValidatorMustReturnBool { .. } => Some(Box::new("Try annotating the validator's return type with Bool")),
             Error::WrongValidatorArity { .. } => Some(Box::new("Validators require a minimum number of arguments please add the missing arguments.\nIf you don't need one of the required arguments use an underscore `_datum`.")),
-            Error::TestFailure { .. }  => None,
+            Error::TestFailure { evaluation_hint, .. }  =>{
+                match evaluation_hint {
+                    None => None,
+                    Some(hint) => {
+                        let budget = ExBudget { mem: i64::MAX, cpu: i64::MAX, };
+                        let left = pretty::boxed("left", match hint.left.eval(budget) {
+                            (Ok(term), _, _) => format!("{term}"),
+                            (Err(err), _, _) => format!("{err}"),
+                        });
+                        let right = pretty::boxed("right", match hint.right.eval(budget) {
+                            (Ok(term), _, _) => format!("{term}"),
+                            (Err(err), _, _) => format!("{err}"),
+                        });
+                        let msg = match hint.bin_op {
+                            BinOp::And => Some(format!("{left}\n\nand\n\n{right}\n\nshould both be true.")),
+                            BinOp::Or => Some(format!("{left}\n\nor\n\n{right}\n\nshould be true.")),
+                            BinOp::Eq => Some(format!("{left}\n\nshould be equal to\n\n{right}")),
+                            BinOp::NotEq => Some(format!("{left}\n\nshould not be equal to\n\n{right}")),
+                            BinOp::LtInt => Some(format!("{left}\n\nshould be lower than\n\n{right}")),
+                            BinOp::LtEqInt => Some(format!("{left}\n\nshould be lower than or equal to\n\n{right}")),
+                            BinOp::GtEqInt => Some(format!("{left}\n\nshould be greater than\n\n{right}")),
+                            BinOp::GtInt => Some(format!("{left}\n\nshould be greater than or equal to\n\n{right}")),
+                            _ => None
+                        }?;
+                        Some(Box::new(msg))
+                    }
+                }
+            },
         }
     }
 

crates/project/src/lib.rs

@@ -25,9 +25,14 @@ use pallas::{
     ledger::{addresses::Address, primitives::babbage},
 };
 use pallas_traverse::ComputeHash;
-use script::Script;
+use script::{EvalHint, EvalInfo, Script};
 use serde_json::json;
-use telemetry::{EvalInfo, EventListener};
+use std::{
+    collections::HashMap,
+    fs,
+    path::{Path, PathBuf},
+};
+use telemetry::EventListener;
 use uplc::{
     ast::{Constant, DeBruijn, Program, Term},
     machine::cost_model::ExBudget,
@@ -159,6 +164,7 @@ where
                             Some(Error::TestFailure {
                                 name: e.script.name.clone(),
                                 path: e.script.input_path.clone(),
+                                evaluation_hint: e.script.evaluation_hint.clone(),
                             })
                         }
                     })
@@ -472,7 +478,13 @@ where
 
             let program = generator.generate(body, arguments, true);
 
-            let script = Script::new(input_path, module_name, name, program.try_into().unwrap());
+            let script = Script::new(
+                input_path,
+                module_name,
+                name,
+                program.try_into().unwrap(),
+                None,
+            );
 
             programs.push(script);
         }
@@ -571,6 +583,25 @@ where
                 &self.module_types,
             );
 
+            let evaluation_hint = if let Some((bin_op, left_src, right_src)) = func_def.test_hint()
+            {
+                let left = CodeGenerator::new(&functions, &data_types, &self.module_types)
+                    .generate(*left_src, vec![], false)
+                    .try_into()
+                    .unwrap();
+                let right = CodeGenerator::new(&functions, &data_types, &self.module_types)
+                    .generate(*right_src, vec![], false)
+                    .try_into()
+                    .unwrap();
+                Some(EvalHint {
+                    bin_op,
+                    left,
+                    right,
+                })
+            } else {
+                None
+            };
+
             let program = generator.generate(body.clone(), arguments.clone(), false);
 
             let script = Script::new(
@@ -578,6 +609,7 @@ where
                 module_name,
                 name.to_string(),
                 program.try_into().unwrap(),
+                evaluation_hint,
             );
 
             programs.push(script);