Resolve issue #599

src/lib/environment.ts

@@ -127,7 +127,7 @@ export interface TwingEnvironment {
      *
      * When a template is encountered, Twing environment emits a `template` event with the name of the encountered template and the source of the template that initiated the loading.
      */
-    on(eventName: "load", listener: (name: string, from: TwingSource | null) => void): void;
+    on(eventName: "load", listener: (name: string, from: string | null) => void): void;
 
     /**
      * Converts a token list to a template.

test/tests/unit/lib/environment/load-template.ts

@@ -2,6 +2,7 @@ import * as tape from "tape";
 import {createEnvironment} from "../../../../../src/lib/environment";
 import {createFilesystemLoader, TwingFilesystemLoaderFilesystem} from "../../../../../src/lib/loader/filesystem";
 import {spy} from "sinon";
+import {createArrayLoader} from "../../../../../src/lib/loader/array";
 
 tape('createEnvironment::loadTemplate', ({test}) => {
     test('cache the loaded template under it fully qualified name', ({same, end}) => {
@@ -40,4 +41,29 @@ tape('createEnvironment::loadTemplate', ({test}) => {
             })
             .finally(end);
     });
+
+    test('emits a "load" event', ({same, end}) => {
+        const environment = createEnvironment(createArrayLoader({
+            index: `{{ include("partial") }}`,
+            partial: ``
+        }));
+
+        const loadedTemplates: Array<[string, string | null]> = [];
+
+        environment.on("load", (name, from) => {
+            loadedTemplates.push([name, from]);
+        });
+
+        return environment.loadTemplate(('index'))
+            .then((template) => {
+                return template.render({});
+            })
+            .then(() => {
+                same(loadedTemplates, [
+                    ['index', null],
+                    ['partial', 'index']
+                ]);
+            })
+            .finally(end);
+    });
 });