Add import helper to load ESM modules

lib/nodo/core.rb

@@ -82,7 +82,7 @@ def generate_core_code
 
       def generate_class_code
         <<~JS
-          (() => {
+          (async () => {
             const __nodo_klass__ = { nodo: global.nodo };
             #{dependencies.map(&:to_js).join}
             #{constants.map(&:to_js).join}
@@ -109,7 +109,13 @@ def finalize_context(context_id)
       def require(*mods)
         deps = mods.last.is_a?(Hash) ? mods.pop : {}
         mods = mods.map { |m| [m, m] }.to_h
-        self.dependencies = dependencies + mods.merge(deps).map { |name, package| Dependency.new(name, package) }
+        self.dependencies = dependencies + mods.merge(deps).map { |name, package| Dependency.new(name, package, type: :cjs) }
+      end
+
+      def import(*mods)
+        deps = mods.last.is_a?(Hash) ? mods.pop : {}
+        mods = mods.map { |m| [m, m] }.to_h
+        self.dependencies = dependencies + mods.merge(deps).map { |name, package| Dependency.new(name, package, type: :esm) }
       end
 
       def function(name, _code = nil, timeout: Nodo.timeout, code: nil, &block)

lib/nodo/dependency.rb

@@ -1,12 +1,22 @@
 module Nodo
   class Dependency
-    attr_reader :name, :package
-    
-    def initialize(name, package)
-      @name, @package = name, package
+    attr_reader :name, :package, :type
+
+    def initialize(name, package, type:)
+      @name, @package, @type = name, package, type
     end
-  
+
     def to_js
+      case type
+      when :cjs then to_cjs
+      when :esm then to_esm
+      else raise "Unknown dependency type: #{type}"
+      end
+    end
+
+    private
+
+    def to_cjs
       <<~JS
         const #{name} = __nodo_klass__.#{name} = (() => {
           try {
@@ -18,5 +28,18 @@ def to_js
         })();
       JS
     end
+
+    def to_esm
+      <<~JS
+        const #{name} = __nodo_klass__.#{name} = await (async () => {
+          try {
+            return await nodo.import(#{package.to_json});
+          } catch(e) {
+            e.nodo_dependency = #{package.to_json};
+            throw e;
+          }
+        })();
+      JS
+    end
   end
 end

lib/nodo/nodo.cjs

@@ -99,8 +99,12 @@ module.exports = (function() {
 
           try {
             if (DEFINE_METHOD == method) {
-              classes[class_name] = vm.runInThisContext(input, class_name);
-              respond_with_data(res, class_name, start);
+              Promise.resolve(vm.runInThisContext(input, class_name)).then((result) => {
+                classes[class_name] = result;
+                respond_with_data(res, class_name, start);
+              }).catch((error) => {
+                respond_with_error(res, 500, error);
+              })
             } else if (EVALUATE_METHOD == method) {
               Promise.resolve(vm.runInNewContext(input, context)).then((result) => {
                 respond_with_data(res, result, start);

test/nodo_test.rb

@@ -167,8 +167,8 @@ def test_logging
       assert_match /Nodo::JavaScriptError/, Nodo.logger.errors.first
     end
   end
-  
-  def test_dependency_error
+
+  def test_require_dependency_error
     with_logger nil do
       nodo = Class.new(Nodo::Core) do
         require 'foobarfoo'
@@ -260,9 +260,44 @@ def test_dynamic_imports_in_evaluation
     uuid = nodo.new.evaluate("nodo.import('uuid').then((uuid) => uuid.v4()).catch((e) => null)")
     assert_uuid uuid
   end
-
+
+  def test_import
+    nodo = Class.new(Nodo::Core) do
+      import :fs
+      function :exists_file, "(file) => fs.existsSync(file)"
+    end
+    assert_equal true, nodo.instance.exists_file(__FILE__)
+    assert_equal false, nodo.instance.exists_file('FOOBARFOO')
+  end
+
+  def test_import_npm
+    nodo = Class.new(Nodo::Core) do
+      import :uuid
+      function :v4, "() => uuid.v4()"
+    end
+    assert uuid = nodo.new.v4
+    assert_equal 36, uuid.size
+  end
+
+  def test_import_dependency_error
+    with_logger nil do
+      nodo = Class.new(Nodo::Core) do
+        import 'foobarfoo'
+      end
+      assert_raises Nodo::DependencyError do
+        nodo.new
+      end
+    end
+  end
+
+  def test_evaluation_can_access_imports
+    nodo = Class.new(Nodo::Core) { import :uuid }
+    uuid = nodo.new.evaluate('uuid.v4()')
+    assert_uuid uuid
+  end
+
   private
-  
+
   def test_logger
     Object.new.instance_exec do
       def errors; @errors ||= []; end