Exit(0) is success when running wasm executables

cli/src/lib.rs

@@ -371,15 +371,22 @@ fn run_with_wasmer(wasm_path: &std::path::Path, args: &[String]) {
 
     // Then, we get the import object related to our WASI
     // and attach it to the Wasm instance.
-    let import_object = wasi_env
-        .import_object(&module)
-        .unwrap_or_else(|_| wasmer::imports!());
+    let import_object = wasi_env.import_object(&module).unwrap();
 
     let instance = Instance::new(&module, &import_object).unwrap();
 
     let start = instance.exports.get_function("_start").unwrap();
 
-    start.call(&[]).unwrap();
+    use wasmer_wasi::WasiError;
+    match start.call(&[]) {
+        Ok(_) => {}
+        Err(e) => match e.downcast::<WasiError>() {
+            Ok(WasiError::Exit(0)) => {
+                // we run the `_start` function, so exit(0) is expected
+            }
+            other => panic!("Wasmer error: {:?}", other),
+        },
+    }
 }
 
 enum Backend {

cli/tests/cli_run.rs

@@ -603,7 +603,7 @@ mod cli_run {
     }
 }
 
-#[cfg(feature = "wasm32-cli-run")]
+#[allow(dead_code)]
 fn run_with_wasmer(wasm_path: &std::path::Path, stdin: &[&str]) -> String {
     use std::io::Write;
     use wasmer::{Instance, Module, Store};
@@ -647,7 +647,22 @@ fn run_with_wasmer(wasm_path: &std::path::Path, stdin: &[&str]) -> String {
     let start = instance.exports.get_function("_start").unwrap();
 
     match start.call(&[]) {
-        Ok(_) => {
+        Ok(_) => read_wasi_stdout(wasi_env),
+        Err(e) => {
+            use wasmer_wasi::WasiError;
+            match e.downcast::<WasiError>() {
+                Ok(WasiError::Exit(0)) => {
+                    // we run the `_start` function, so exit(0) is expected
+                    read_wasi_stdout(wasi_env)
+                }
+                other => format!("Something went wrong running a wasm test: {:?}", other),
+            }
+        }
+    }
+}
+
+#[allow(dead_code)]
+fn read_wasi_stdout(wasi_env: wasmer_wasi::WasiEnv) -> String {
     let mut state = wasi_env.state.lock().unwrap();
 
     match state.fs.stdout_mut() {
@@ -660,8 +675,3 @@ fn run_with_wasmer(wasm_path: &std::path::Path, stdin: &[&str]) -> String {
         _ => todo!(),
     }
 }
-        Err(e) => {
-            panic!("Something went wrong running a wasm test:\n{:?}", e);
-        }
-    }
-}