diff --git a/src/services/code_block_theme.spec.ts b/src/services/code_block_theme.spec.ts
new file mode 100644
index 000000000..84482b416
--- /dev/null
+++ b/src/services/code_block_theme.spec.ts
@@ -0,0 +1,21 @@
+import { describe, expect, it } from "vitest";
+import { getStylesDirectory, readThemesFromFileSystem } from "./code_block_theme.js";
+
+import themeNames from "./code_block_theme_names.json" with { type: "json" };
+
+describe("Code block theme", () => {
+    it("all themes are mapped", () => {
+        const themes = readThemesFromFileSystem(getStylesDirectory());
+
+        const mappedThemeNames = new Set(Object.values(themeNames));
+        const unmappedThemeNames = new Set<string>();
+
+        for (const theme of themes) {
+            if (!mappedThemeNames.has(theme.title)) {
+                unmappedThemeNames.add(theme.title);
+            }
+        }
+
+        expect(unmappedThemeNames.size, `Unmapped themes: ${Array.from(unmappedThemeNames).join(", ")}`).toBe(0);
+    });
+});
diff --git a/src/services/code_block_theme.ts b/src/services/code_block_theme.ts
index 8351b2519..8a3964fcd 100644
--- a/src/services/code_block_theme.ts
+++ b/src/services/code_block_theme.ts
@@ -44,7 +44,7 @@ export function listSyntaxHighlightingThemes() {
     };
 }
 
-function getStylesDirectory() {
+export function getStylesDirectory() {
     if (isElectron && !isDev) {
         return "styles";
     }
@@ -60,7 +60,7 @@ function getStylesDirectory() {
  * @param path the path to read from. Usually this is the highlight.js `styles` directory.
  * @returns the list of themes.
  */
-function readThemesFromFileSystem(path: string): ColorTheme[] {
+export function readThemesFromFileSystem(path: string): ColorTheme[] {
     return fs
         .readdirSync(path)
         .filter((el) => el.endsWith(".min.css"))