Lockdown kata test prints as well as prints of various values (#249)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

src/tests/interpreter/mod.rs

@@ -139,9 +139,10 @@ pub fn eval_file(
     query: &str,
     enable_tracing: bool,
     strict: bool,
-) -> Result<Vec<Value>> {
+) -> Result<(Vec<Value>, Vec<String>)> {
     let mut engine: Engine = Engine::new();
     engine.set_strict_builtin_errors(strict);
+    engine.set_gather_prints(true);
 
     #[cfg(feature = "coverage")]
     engine.set_enable_coverage(true);
@@ -206,7 +207,7 @@ pub fn eval_file(
         }
     }
 
-    Ok(results)
+    Ok((results, engine.take_prints()?))
 }
 
 #[derive(PartialEq, Debug)]
@@ -254,6 +255,7 @@ struct TestCase {
     query: String,
     sort_bindings: Option<bool>,
     want_result: Option<ValueOrVec>,
+    want_prints: Option<Vec<String>>,
     no_result: Option<bool>,
     skip: Option<bool>,
     error: Option<String>,
@@ -333,7 +335,7 @@ fn yaml_test_impl(file: &str) -> Result<()> {
             enable_tracing,
             case.strict,
         ) {
-            Ok(results) => match case.want_result {
+            Ok((results, prints)) => match case.want_result {
                 Some(want_result) => {
                     let mut expected_results = vec![];
                     match want_result {
@@ -344,6 +346,18 @@ fn yaml_test_impl(file: &str) -> Result<()> {
                     }
 
                     check_output(&results, &expected_results)?;
+                    if let Some(expected_prints) = case.want_prints {
+                        assert_eq!(expected_prints.len(), prints.len());
+                        for (idx, ep) in expected_prints.into_iter().enumerate() {
+                            if ep != prints[idx] {
+                                std::println!(
+                                    "print mismatch :\n{}",
+                                    prettydiff::diff_chars(&ep, &prints[idx])
+                                );
+                                panic!("exiting");
+                            }
+                        }
+                    }
                 }
                 _ if case.no_result == Some(true) => (),
                 _ => bail!("eval succeeded and did not produce any errors"),