test(assets): implement end-to-end asset manager and mod overlay streaming test

crates/molotov-core/tests/asset_manager_test.rs

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use molotov_core::assets::c_api::*;
+use std::ffi::CString;
+
+#[test]
+fn test_end_to_end_asset_and_mod_overlay_streaming() {
+    // Register base asset and mod override
+    let mgr_handle = register_test_asset("content/fonts/arial.ttf", b"DEFAULT_FONT_DATA".to_vec());
+    if let Ok(mut mgr) = GLOBAL_ASSET_MANAGER.write() {
+        mgr.add_mod_override("content/fonts/arial.ttf", b"CUSTOM_COMIC_SANS_MOD".to_vec());
+    }
+
+    unsafe {
+        let path = CString::new("content/fonts/arial.ttf").unwrap();
+        let asset = AAssetManager_open(mgr_handle, path.as_ptr(), 1);
+        assert!(!asset.is_null());
+
+        let len = AAsset_getLength(asset);
+        assert_eq!(len, 21);
+
+        let mut out = vec![0u8; len as usize];
+        let read = AAsset_read(asset, out.as_mut_ptr() as *mut _, len as usize);
+        assert_eq!(read, 21);
+        assert_eq!(&out, b"CUSTOM_COMIC_SANS_MOD", "Must load custom user mod");
+
+        AAsset_close(asset);
+    }
+}