dependencies and changes to test in firefox headlessly

.devcontainer/devcontainer.json

@@ -2,5 +2,6 @@
 	"image": "mcr.microsoft.com/devcontainers/universal:2",
 	"features": {
 		"ghcr.io/devcontainers-community/npm-features/typescript:1": {}
-	}
+	},
+	"postCreateCommand": "apt-get update && apt-get install -y firefox xvfb libxss1 libappindicator1 libindicator7"
 }

package.json

@@ -12,6 +12,6 @@
   "scripts": {
     "build": "dev-scripts/build-extension.sh",
     "pretest": "tsc",
-    "test": "jasmine-browser-runner runSpecs"
+    "test": "xvfb-run -a jasmine-browser-runner runSpecs"
   }
 }

spec/indexeddb_spec.js

@@ -0,0 +1,5 @@
+describe("hello", function() {
+    it("world", function() {
+        expect(true).toBe(true)
+    })
+})

spec/support/jasmine-browser.mjs

@@ -3,9 +3,9 @@ export default {
   // srcFiles should usually be left empty when using ES modules, because you'll
   // explicitly import sources from your specs.
   srcFiles: [],
-  specDir: ".",
+  specDir: "./spec",
   specFiles: [
-    "spec/**/*[sS]pec.?(m)js"
+    "**/*[sS]pec.?(m)js"
   ],
   helpers: [
     "spec/helpers/**/*.?(m)js"
@@ -33,6 +33,7 @@ export default {
   hostname: "localhost",
 
   browser: {
-    name: "firefox"
+    name: "firefox",
+    headless: true
   }
 };