Adding a note to hint --nocapture usage

dont display error if not executed

src/cargo/ops/cargo_test.rs

@@ -149,7 +149,7 @@ fn run_unit_tests(
                 unit: unit.clone(),
                 kind: test_kind,
             };
-            report_test_error(ws, &options.compile_opts, &unit_err, e);
+            report_test_error(ws, test_args, &options.compile_opts, &unit_err, e);
             errors.push(unit_err);
             if !options.no_fail_fast {
                 return Err(CliError::code(code));
@@ -275,7 +275,7 @@ fn run_doc_tests(
                 unit: unit.clone(),
                 kind: TestKind::Doctest,
             };
-            report_test_error(ws, &options.compile_opts, &unit_err, e);
+            report_test_error(ws, test_args, &options.compile_opts, &unit_err, e);
             errors.push(unit_err);
             if !options.no_fail_fast {
                 return Err(CliError::code(code));
@@ -407,6 +407,7 @@ fn no_fail_fast_err(
 /// Displays an error on the console about a test failure.
 fn report_test_error(
     ws: &Workspace<'_>,
+    test_args: &[&str],
     opts: &ops::CompileOptions,
     unit_err: &UnitTestError,
     test_error: anyhow::Error,
@@ -420,13 +421,23 @@ fn report_test_error(
     let mut err = format_err!("{}, to rerun pass `{}`", which, unit_err.cli_args(ws, opts));
     // Don't show "process didn't exit successfully" for simple errors.
     // libtest exits with 101 for normal errors.
-    let is_simple = test_error
+    let (is_simple, executed) = test_error
         .downcast_ref::<ProcessError>()
         .and_then(|proc_err| proc_err.code)
-        .map_or(false, |code| code == 101);
+        .map_or((false, false), |code| (code == 101, true));
+
     if !is_simple {
         err = test_error.context(err);
     }
 
     crate::display_error(&err, &mut ws.config().shell());
+
+    let harness: bool = unit_err.unit.target.harness();
+    let nocapture: bool = test_args.contains(&"--nocapture");
+
+    if !is_simple && executed && harness && !nocapture {
+        drop(ws.config().shell().note(
+            "test exited abnormally; to see the full output pass --nocapture to the harness.",
+        ));
+    }
 }

tests/testsuite/test.rs

@@ -4792,6 +4792,21 @@ error: test failed, to rerun pass `--test t1`
 [RUNNING] tests/t2.rs (target/debug/deps/t2[..])
 error: test failed, to rerun pass `--test t2`
 
+Caused by:
+  process didn't exit successfully: `[ROOT]/foo/target/debug/deps/t2[..]` (exit [..]: 4)
+note: test exited abnormally; to see the full output pass --nocapture to the harness.
+",
+        )
+        .with_status(4)
+        .run();
+
+    p.cargo("test --test t2 -- --nocapture")
+        .with_stderr(
+            "\
+[FINISHED] test [..]
+[RUNNING] tests/t2.rs (target/debug/deps/t2[..])
+error: test failed, to rerun pass `--test t2`
+
 Caused by:
   process didn't exit successfully: `[ROOT]/foo/target/debug/deps/t2[..]` (exit [..]: 4)
 ",
@@ -4823,6 +4838,28 @@ error: test failed, to rerun pass `--test t1`
 [RUNNING] tests/t2.rs (target/debug/deps/t2[..])
 error: test failed, to rerun pass `--test t2`
 
+Caused by:
+  process didn't exit successfully: `[ROOT]/foo/target/debug/deps/t2[..]` (exit [..]: 4)
+note: test exited abnormally; to see the full output pass --nocapture to the harness.
+error: 2 targets failed:
+    `--test t1`
+    `--test t2`
+",
+        )
+        .with_status(101)
+        .run();
+
+    p.cargo("test --no-fail-fast -- --nocapture")
+        .with_stderr(
+            "\
+[FINISHED] test [..]
+[RUNNING] tests/t1.rs (target/debug/deps/t1[..])
+thread 't' panicked at 'this is a normal error', tests/t1[..]
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+error: test failed, to rerun pass `--test t1`
+[RUNNING] tests/t2.rs (target/debug/deps/t2[..])
+error: test failed, to rerun pass `--test t2`
+
 Caused by:
   process didn't exit successfully: `[ROOT]/foo/target/debug/deps/t2[..]` (exit [..]: 4)
 error: 2 targets failed: