lean_compiler: avoid duplicate compile-and-run output

crates/lean_compiler/src/lib.rs

@@ -180,7 +180,6 @@ pub fn try_compile_and_run(
     let bytecode = try_compile_program(input)?;
     let witness = ExecutionWitness::default();
     let result = try_execute_bytecode(&bytecode, public_input, &witness, profiler)?;
-    println!("{}", result.metadata.display());
     Ok(result.metadata.display())
 }
 

crates/lean_compiler/tests/try_compile_and_run_output.rs

@@ -0,0 +1,52 @@
+use std::process::Command;
+
+use backend::PrimeCharacteristicRing;
+use lean_compiler::{ProgramSource, try_compile_and_run};
+use lean_vm::{DIGEST_LEN, F};
+
+const CHILD_TEST: &str = "child_calls_try_compile_and_run";
+const CHILD_ENV: &str = "LEAN_COMPILER_TRY_COMPILE_AND_RUN_CHILD";
+
+#[test]
+fn try_compile_and_run_does_not_print_summary() {
+    // Re-exec this test binary so stdout capture stays process-local and does not
+    // depend on global test harness state. `--exact` avoids recursively running
+    // this parent test in the child process.
+    let output = Command::new(std::env::current_exe().unwrap())
+        .arg("--exact")
+        .arg(CHILD_TEST)
+        .arg("--nocapture")
+        .env(CHILD_ENV, "1")
+        .output()
+        .unwrap();
+
+    assert!(
+        output.status.success(),
+        "child test failed\nstdout:\n{}\nstderr:\n{}",
+        String::from_utf8_lossy(&output.stdout),
+        String::from_utf8_lossy(&output.stderr),
+    );
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    assert!(
+        !stdout.contains("STATS"),
+        "try_compile_and_run unexpectedly printed the execution summary:\n{stdout}"
+    );
+}
+
+#[test]
+fn child_calls_try_compile_and_run() {
+    // This test only does real work in the child process spawned above.
+    if std::env::var_os(CHILD_ENV).is_none() {
+        return;
+    }
+
+    let summary = try_compile_and_run(
+        &ProgramSource::Raw("def main():\n    return\n".to_string()),
+        &[F::ZERO; DIGEST_LEN],
+        false,
+    )
+    .unwrap();
+
+    assert!(summary.contains("STATS"));
+}