Add a few CLI tests for WASI. (#1281)

While here, move rs2wasm-add-func.wat into the same directory as the
other .wat tests to keep things tidy.

tests/cli_tests.rs

@@ -103,6 +103,23 @@ fn run_wasmtime_unreachable_wat() -> Result<()> {
     assert_eq!(code, 128 + libc::SIGABRT);
     #[cfg(windows)]
     assert_eq!(code, 3);
-
+    Ok(())
+}
+
+// Run a simple WASI hello world, snapshot0 edition.
+#[test]
+fn hello_wasi_snapshot0() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/hello_wasi_snapshot0.wat")?;
+    let stdout = run_wasmtime(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    assert_eq!(stdout, "Hello, world!\n");
+    Ok(())
+}
+
+// Run a simple WASI hello world, snapshot1 edition.
+#[test]
+fn hello_wasi_snapshot1() -> Result<()> {
+    let wasm = build_wasm("tests/wasm/hello_wasi_snapshot1.wat")?;
+    let stdout = run_wasmtime(&[wasm.path().to_str().unwrap(), "--disable-cache"])?;
+    assert_eq!(stdout, "Hello, world!\n");
     Ok(())
 }