diff --git a/src/config/note.config.spec.ts b/src/config/note.config.spec.ts
new file mode 100644
index 000000000..3949a2e91
--- /dev/null
+++ b/src/config/note.config.spec.ts
@@ -0,0 +1,166 @@
+/*
+ * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import mockedEnv from 'mocked-env';
+
+import noteConfig from './note.config';
+
+describe('noteConfig', () => {
+  const forbiddenNoteIds = ['forbidden_1', 'forbidden_2'];
+  const forbiddenNoteId = 'single_forbidden_id';
+  const invalidforbiddenNoteIds = ['', ''];
+  const maxDocumentLength = 1234;
+  const negativeMaxDocumentLength = -123;
+  const floatMaxDocumentLength = 2.71;
+  const invalidMaxDocumentLength = 'not-a-max-document-length';
+
+  describe('correctly parses config', () => {
+    it('when given correct and complete environment variables', async () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: forbiddenNoteIds.join(' , '),
+          HD_MAX_DOCUMENT_LENGTH: maxDocumentLength.toString(),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      const config = noteConfig();
+      expect(config.forbiddenNoteIds).toHaveLength(forbiddenNoteIds.length);
+      expect(config.forbiddenNoteIds).toEqual(forbiddenNoteIds);
+      expect(config.maxDocumentLength).toEqual(maxDocumentLength);
+      restore();
+    });
+
+    it('when no HD_FORBIDDEN_NOTE_IDS is set', () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_MAX_DOCUMENT_LENGTH: maxDocumentLength.toString(),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      const config = noteConfig();
+      expect(config.forbiddenNoteIds).toHaveLength(0);
+      expect(config.maxDocumentLength).toEqual(maxDocumentLength);
+      restore();
+    });
+
+    it('when no HD_MAX_DOCUMENT_LENGTH is set', () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: forbiddenNoteIds.join(' , '),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      const config = noteConfig();
+      expect(config.forbiddenNoteIds).toHaveLength(forbiddenNoteIds.length);
+      expect(config.forbiddenNoteIds).toEqual(forbiddenNoteIds);
+      expect(config.maxDocumentLength).toEqual(100000);
+      restore();
+    });
+
+    it('when HD_FORBIDDEN_NOTE_IDS is a single item', () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: forbiddenNoteId,
+          HD_MAX_DOCUMENT_LENGTH: maxDocumentLength.toString(),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      const config = noteConfig();
+      expect(config.forbiddenNoteIds).toHaveLength(1);
+      expect(config.forbiddenNoteIds[0]).toEqual(forbiddenNoteId);
+      expect(config.maxDocumentLength).toEqual(maxDocumentLength);
+      restore();
+    });
+  });
+  describe('throws error', () => {
+    it('when given a non-valid HD_FORBIDDEN_NOTE_IDS', async () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: invalidforbiddenNoteIds.join(' , '),
+          HD_MAX_DOCUMENT_LENGTH: maxDocumentLength.toString(),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      expect(() => noteConfig()).toThrow(
+        '"forbiddenNoteIds[0]" is not allowed to be empty',
+      );
+      restore();
+    });
+
+    it('when given a negative HD_MAX_DOCUMENT_LENGTH', async () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: forbiddenNoteIds.join(' , '),
+          HD_MAX_DOCUMENT_LENGTH: negativeMaxDocumentLength.toString(),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      expect(() => noteConfig()).toThrow(
+        '"HD_MAX_DOCUMENT_LENGTH" must be a positive number',
+      );
+      restore();
+    });
+
+    it('when given a non-integer HD_MAX_DOCUMENT_LENGTH', async () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: forbiddenNoteIds.join(' , '),
+          HD_MAX_DOCUMENT_LENGTH: floatMaxDocumentLength.toString(),
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      expect(() => noteConfig()).toThrow(
+        '"HD_MAX_DOCUMENT_LENGTH" must be an integer',
+      );
+      restore();
+    });
+
+    it('when given a non-number HD_MAX_DOCUMENT_LENGTH', async () => {
+      const restore = mockedEnv(
+        {
+          /* eslint-disable @typescript-eslint/naming-convention */
+          HD_FORBIDDEN_NOTE_IDS: forbiddenNoteIds.join(' , '),
+          HD_MAX_DOCUMENT_LENGTH: invalidMaxDocumentLength,
+          /* eslint-enable @typescript-eslint/naming-convention */
+        },
+        {
+          clear: true,
+        },
+      );
+      expect(() => noteConfig()).toThrow(
+        '"HD_MAX_DOCUMENT_LENGTH" must be a number',
+      );
+      restore();
+    });
+  });
+});