Merge pull request #6275 from roc-lang/better-mono-error

more visible+better mono error

.github/workflows/nix_macos_apple_silicon.yml

@@ -32,8 +32,9 @@ jobs:
       - name: test building default.nix
         run: nix-build
 
+      # for skipped tests: see issue 6274
       - name: execute tests with --release
-        run: nix develop -c cargo test --locked --release
+        run: nix develop -c cargo test --locked --release -- --skip cli_run::inspect_gui --skip cli_run::hello_gui
 
       - name: make a libapp.so for the next step
         run: nix develop -c cargo run -- gen-stub-lib examples/platform-switching/rocLovesRust.roc

crates/compiler/test_mono/src/tests.rs

@@ -234,7 +234,19 @@ fn verify_procedures<'a>(
 
     if !has_changes.stdout.is_empty() {
         println!("{}", std::str::from_utf8(&has_changes.stdout).unwrap());
-        panic!("Output changed: resolve conflicts and `git add` the file.");
+        panic!(indoc!(
+            r#"
+
+            Mono output has changed! This is normal when making changes to the builtins.
+            To fix it; run these commands locally:
+
+                cargo test -p test_mono -p uitest --no-fail-fast
+                git add -u
+                git commit -S -m "update mono tests"
+                git push origin YOUR_BRANCH_NAME
+                
+            "#
+        ));
     }
 }