Move workspace creation outside of runtime instantiation

tests/runtime/mod.rs

@@ -1,19 +1,14 @@
-mod utils;
 mod wasi;
 
 use cranelift_codegen::settings;
 use cranelift_native;
-use std::path::Path;
 use wasmtime_jit::Context;
 
-pub fn run_test<P: AsRef<Path>>(path: P) -> Result<(), String> {
-    // Load in the wasm testcase
-    let data = utils::read_wasm(path.as_ref())?;
-    let bin_name = utils::extract_exec_name_from_path(path.as_ref())?;
-
-    // Prepare workspace
-    let workspace = utils::prepare_workspace(&bin_name)?;
-
+pub fn instantiate<S: AsRef<str>>(
+    data: &[u8],
+    bin_name: S,
+    workspace: Option<S>,
+) -> Result<(), String> {
     // Prepare runtime
     let isa_builder =
         cranelift_native::builder().map_err(|_| "host machine is not a supported target")?;
@@ -21,16 +16,30 @@ pub fn run_test<P: AsRef<Path>>(path: P) -> Result<(), String> {
     let isa = isa_builder.finish(settings::Flags::new(flag_builder));
     let mut context = Context::with_isa(isa);
     let global_exports = context.get_global_exports();
-    let preopen_dir = wasi_common::preopen_dir(&workspace)
-        .map_err(|e| format!("error while preopening directory '{}': {}", workspace, e))?;
+
+    let get_preopens = |workspace: Option<S>| -> Result<Vec<_>, String> {
+        if let Some(workspace) = workspace {
+            let preopen_dir = wasi_common::preopen_dir(workspace.as_ref()).map_err(|e| {
+                format!(
+                    "error while preopening directory '{}': {}",
+                    workspace.as_ref(),
+                    e
+                )
+            })?;
+
+            Ok(vec![(".".to_owned(), preopen_dir)])
+        } else {
+            Ok(vec![])
+        }
+    };
 
     context.name_instance(
         "wasi_unstable".to_owned(),
         wasi::instantiate_wasi(
             "",
             global_exports,
-            &[(".".to_owned(), preopen_dir)],
-            &[bin_name.clone(), ".".to_owned()],
+            &get_preopens(workspace)?,
+            &[bin_name.as_ref().to_owned(), ".".to_owned()],
             &[],
         )
         .expect("instantiating wasi"),
@@ -40,5 +49,11 @@ pub fn run_test<P: AsRef<Path>>(path: P) -> Result<(), String> {
     context
         .instantiate_module(None, &data)
         .map(|_| ())
-        .map_err(|e| format!("error while processing main module '{}': {}", bin_name, e))
+        .map_err(|e| {
+            format!(
+                "error while processing main module '{}': {}",
+                bin_name.as_ref(),
+                e
+            )
+        })
 }