test: reset global state between each test and mock bg-handler path

src/responsive-image-plugin.ts

@@ -36,11 +36,21 @@ let generationStatus: 'ready' | 'processing' | 'completed' = 'ready';
 let releaseWhenGenerationCompletedTimeout: NodeJS.Timeout;
 let generationCompleted: Promise<void>;
 
+function getBgHandlerPath() {
+  // Short circuit the path since it's not available at test time,
+  // since we don't run an intermediate build step
+  if (process.env.NODE_ENV === 'test') {
+    return '';
+  }
+
+  return require.resolve(join(__dirname, 'bg-handler'));
+}
+
 class ResponsiveImagePlugin {
   public static loader = require.resolve(
     join(__dirname, 'responsive-image-loader'),
   );
-  public static bgHandler = require.resolve(join(__dirname, 'bg-handler'));
+  public static bgHandler = getBgHandlerPath();
 
   // Shared with the loader
   public options: ResponsiveImagePluginConfig;

test/responsive-image-loader.spec.ts

@@ -1,8 +1,10 @@
-import { describe, expect, it } from '@jest/globals';
+import { beforeEach, describe, expect, it } from '@jest/globals';
 import { writeFileSync } from 'fs';
 import { join, resolve } from 'path';
 import {
   IMG_TAG_PLACEHOLDER_PATTERN,
+  metadataCache,
+  urlReplaceMap,
   URL_PLACEHOLDER_PATTERN,
 } from 'src/parsing';
 import { existsOrCreateDirectory } from '../src/base';
@@ -47,6 +49,15 @@ describe('Responsive image loader', () => {
   });
 
   describe('Plain images', () => {
+    beforeEach(() => {
+      // Cleans the urlReplaceMap and metadataCache before each test,
+      // otherwise metadata generation would be skipped or old hashed URIs could be used
+      for (const key in urlReplaceMap) {
+        delete urlReplaceMap[key];
+      }
+      metadataCache.clear();
+    });
+
     describe('conversion disabled', () => {
       const conversionDisabled = { conversion: { converter: null } };