Fix 'not enough arguments' during wasmtime run (#858)

* Fix 'not enough arguments' during wasmtime run

* add simple cli smoke tests

* autogenerate wasm

tests/cli_tests.rs

@@ -0,0 +1,66 @@
+use anyhow::{bail, Result};
+use std::env;
+use std::io::Write;
+use std::path::Path;
+use std::process::{Command, Stdio};
+use tempfile::NamedTempFile;
+
+fn run_wasmtime(args: &[&str]) -> Result<()> {
+    let cargo = env::var("CARGO").unwrap_or("cargo".to_string());
+    let pkg_dir = env!("CARGO_MANIFEST_DIR");
+    let success = Command::new(cargo)
+        .current_dir(pkg_dir)
+        .stdout(Stdio::null())
+        .args(&["run", "-q", "--"])
+        .args(args)
+        .status()?
+        .success();
+    if !success {
+        bail!("Failed to execute wasmtime with: {:?}", args);
+    }
+    Ok(())
+}
+
+fn build_wasm(wat_path: impl AsRef<Path>) -> Result<NamedTempFile> {
+    let mut wasm_file = NamedTempFile::new()?;
+    let wasm = wat::parse_file(wat_path)?;
+    wasm_file.write(&wasm)?;
+    Ok(wasm_file)
+}
+
+// Very basic use case: compile binary wasm file and run specific function with arguments.
+#[test]
+fn run_wasmtime_simple() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/simple.wat")?;
+    run_wasmtime(&[
+        "run",
+        wasm.path().to_str().unwrap(),
+        "--invoke",
+        "simple",
+        "4",
+    ])
+}
+
+// Wasmtime shakk when not enough arguments were provided.
+#[test]
+fn run_wasmtime_simple_fail_no_args() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/simple.wat")?;
+    assert!(
+        run_wasmtime(&["run", wasm.path().to_str().unwrap(), "--invoke", "simple"]).is_err(),
+        "shall fail"
+    );
+    Ok(())
+}
+
+// Running simple wat
+#[test]
+fn run_wasmtime_simple_wat() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/simple.wat")?;
+    run_wasmtime(&[
+        "run",
+        wasm.path().to_str().unwrap(),
+        "--invoke",
+        "simple",
+        "4",
+    ])
+}