Fix flaky CI: load cross-program .so at runtime instead of compile time

The hand test loads lever.so (a different program) via include_bytes!(),
which fails during anchor build's IDL generation step because the .so
files don't exist yet at compile time. Using std::fs::read() defers the
load to test runtime, after anchor build has created the artifacts.

Author: Edward

basics/cross-program-invocation/anchor/programs/hand/tests/test_hand.rs

@@ -50,7 +50,11 @@ fn test_pull_lever_cpi() {
 
     // Load both programs
     let hand_bytes = include_bytes!("../../../target/deploy/hand.so");
-    let lever_bytes = include_bytes!("../../../target/deploy/lever.so");
+    // Use std::fs::read() instead of include_bytes!() for the lever program because
+    // include_bytes!() runs at compile time, and during `anchor build` the IDL generation
+    // step compiles tests before the .so files exist. Since this is a cross-program
+    // dependency (not our own program), lever.so may not be built yet at compile time.
+    let lever_bytes = std::fs::read("target/deploy/lever.so").expect("lever.so not found — run `anchor build` first");
     svm.add_program(hand_program_id, hand_bytes).unwrap();
     svm.add_program(lever_program_id, lever_bytes).unwrap();
     let payer = create_wallet(&mut svm, 10_000_000_000).unwrap();