diff --git a/packages/astro/src/default/utils/__snapshots__/single-part-chapter-and-lesson.json b/packages/astro/src/default/utils/__snapshots__/single-part-chapter-and-lesson.json
new file mode 100644
index 00000000..6ce2dd63
--- /dev/null
+++ b/packages/astro/src/default/utils/__snapshots__/single-part-chapter-and-lesson.json
@@ -0,0 +1,61 @@
+{
+  "parts": {
+    "1-part": {
+      "id": "1-part",
+      "order": 0,
+      "data": {
+        "type": "part",
+        "title": "Basics"
+      },
+      "slug": "part-slug",
+      "chapters": {
+        "1-chapter": {
+          "id": "1-chapter",
+          "order": 0,
+          "data": {
+            "title": "The first chapter in part 1",
+            "type": "chapter"
+          },
+          "slug": "chapter-slug",
+          "lessons": {
+            "1-lesson": {
+              "data": {
+                "type": "lesson",
+                "title": "Welcome to TutorialKit",
+                "template": "default",
+                "i18n": {
+                  "mocked": "default localization"
+                },
+                "openInStackBlitz": true
+              },
+              "id": "1-lesson",
+              "filepath": "1-part/1-chapter/1-lesson/content.md",
+              "order": 0,
+              "part": {
+                "id": "1-part",
+                "title": "Basics"
+              },
+              "chapter": {
+                "id": "1-chapter",
+                "title": "The first chapter in part 1"
+              },
+              "Markdown": "Markdown for tutorial",
+              "slug": "lesson-slug",
+              "files": [
+                "1-part-1-chapter-1-lesson-files.json",
+                []
+              ],
+              "solution": [
+                "1-part-1-chapter-1-lesson-solution.json",
+                []
+              ]
+            }
+          },
+          "firstLessonId": "1-lesson"
+        }
+      },
+      "firstChapterId": "1-chapter"
+    }
+  },
+  "firstPartId": "1-part"
+}
\ No newline at end of file
diff --git a/packages/astro/src/default/utils/__snapshots__/single-part-chapter-and-multiple-lessons.json b/packages/astro/src/default/utils/__snapshots__/single-part-chapter-and-multiple-lessons.json
new file mode 100644
index 00000000..605f6155
--- /dev/null
+++ b/packages/astro/src/default/utils/__snapshots__/single-part-chapter-and-multiple-lessons.json
@@ -0,0 +1,141 @@
+{
+  "parts": {
+    "1-part": {
+      "id": "1-part",
+      "order": 0,
+      "data": {
+        "type": "part",
+        "title": "Basics"
+      },
+      "slug": "part-slug",
+      "chapters": {
+        "1-chapter": {
+          "id": "1-chapter",
+          "order": 0,
+          "data": {
+            "title": "The first chapter in part 1",
+            "type": "chapter"
+          },
+          "slug": "chapter-slug",
+          "lessons": {
+            "1-first": {
+              "data": {
+                "type": "lesson",
+                "title": "Welcome to TutorialKit",
+                "template": "default",
+                "i18n": {
+                  "mocked": "default localization"
+                },
+                "openInStackBlitz": true
+              },
+              "id": "1-first",
+              "filepath": "1-part/1-chapter/1-first/content.md",
+              "order": 0,
+              "part": {
+                "id": "1-part",
+                "title": "Basics"
+              },
+              "chapter": {
+                "id": "1-chapter",
+                "title": "The first chapter in part 1"
+              },
+              "Markdown": "Markdown for tutorial",
+              "slug": "lesson-slug",
+              "files": [
+                "1-part-1-chapter-1-first-files.json",
+                []
+              ],
+              "solution": [
+                "1-part-1-chapter-1-first-solution.json",
+                []
+              ],
+              "next": {
+                "title": "Welcome to TutorialKit",
+                "href": "/part-slug/chapter-slug/lesson-slug"
+              }
+            },
+            "2-second": {
+              "data": {
+                "type": "lesson",
+                "title": "Welcome to TutorialKit",
+                "template": "default",
+                "i18n": {
+                  "mocked": "default localization"
+                },
+                "openInStackBlitz": true
+              },
+              "id": "2-second",
+              "filepath": "1-part/1-chapter/2-second/content.md",
+              "order": 1,
+              "part": {
+                "id": "1-part",
+                "title": "Basics"
+              },
+              "chapter": {
+                "id": "1-chapter",
+                "title": "The first chapter in part 1"
+              },
+              "Markdown": "Markdown for tutorial",
+              "slug": "lesson-slug",
+              "files": [
+                "1-part-1-chapter-2-second-files.json",
+                []
+              ],
+              "solution": [
+                "1-part-1-chapter-2-second-solution.json",
+                []
+              ],
+              "prev": {
+                "title": "Welcome to TutorialKit",
+                "href": "/part-slug/chapter-slug/lesson-slug"
+              },
+              "next": {
+                "title": "Welcome to TutorialKit",
+                "href": "/part-slug/chapter-slug/lesson-slug"
+              }
+            },
+            "3-third": {
+              "data": {
+                "type": "lesson",
+                "title": "Welcome to TutorialKit",
+                "template": "default",
+                "i18n": {
+                  "mocked": "default localization"
+                },
+                "openInStackBlitz": true
+              },
+              "id": "3-third",
+              "filepath": "1-part/1-chapter/3-third/content.md",
+              "order": 2,
+              "part": {
+                "id": "1-part",
+                "title": "Basics"
+              },
+              "chapter": {
+                "id": "1-chapter",
+                "title": "The first chapter in part 1"
+              },
+              "Markdown": "Markdown for tutorial",
+              "slug": "lesson-slug",
+              "files": [
+                "1-part-1-chapter-3-third-files.json",
+                []
+              ],
+              "solution": [
+                "1-part-1-chapter-3-third-solution.json",
+                []
+              ],
+              "prev": {
+                "title": "Welcome to TutorialKit",
+                "href": "/part-slug/chapter-slug/lesson-slug"
+              }
+            }
+          },
+          "firstLessonId": "1-first"
+        }
+      },
+      "firstChapterId": "1-chapter"
+    }
+  },
+  "firstPartId": "1-part"
+}
\ No newline at end of file
diff --git a/packages/astro/src/default/utils/content.spec.ts b/packages/astro/src/default/utils/content.spec.ts
new file mode 100644
index 00000000..277490c2
--- /dev/null
+++ b/packages/astro/src/default/utils/content.spec.ts
@@ -0,0 +1,106 @@
+import * as content from 'astro:content';
+import { expect, test, vi, type TaskContext } from 'vitest';
+import { getTutorial, type CollectionEntryTutorial } from './content';
+
+const getCollection = vi.mocked(content.getCollection);
+vi.mock('astro:content', () => ({ getCollection: vi.fn() }));
+
+// mock DEFAULT_LOCALIZATION so that we don't need to update test results everytime new keys are added there
+vi.mock(import('@tutorialkit/types'), async (importOriginal) => ({
+  ...(await importOriginal()),
+  DEFAULT_LOCALIZATION: { mocked: 'default localization' } as any,
+}));
+
+expect.addSnapshotSerializer({
+  serialize: (val) => JSON.stringify(val, null, 2),
+  test: (value) => !(value instanceof Error),
+});
+
+test('single part, chapter and lesson', async (ctx) => {
+  getCollection.mockReturnValueOnce([
+    { id: 'meta.md', ...tutorial },
+    { id: '1-part/meta.md', ...part },
+    { id: '1-part/1-chapter/meta.md', ...chapter },
+    { id: '1-part/1-chapter/1-lesson/content.md', ...lesson },
+  ]);
+
+  const collection = await getTutorial();
+  await expect(collection).toMatchFileSnapshot(snapshotName(ctx));
+});
+
+test('single part, chapter and multiple lessons', async (ctx) => {
+  getCollection.mockReturnValueOnce([
+    { id: 'meta.md', ...tutorial },
+    { id: '1-part/meta.md', ...part },
+    { id: '1-part/1-chapter/meta.md', ...chapter },
+
+    // 3 lessons
+    { id: '1-part/1-chapter/1-first/content.md', ...lesson },
+    { id: '1-part/1-chapter/2-second/content.md', ...lesson },
+    { id: '1-part/1-chapter/3-third/content.md', ...lesson },
+  ]);
+
+  const collection = await getTutorial();
+
+  const lessons = collection.parts['1-part'].chapters['1-chapter'].lessons;
+  expect(Object.keys(lessons)).toHaveLength(3);
+
+  await expect(collection).toMatchFileSnapshot(snapshotName(ctx));
+});
+
+test('throws when part not found', async () => {
+  getCollection.mockReturnValueOnce([
+    { id: 'meta.md', ...tutorial },
+    { id: '2-part/meta.md', ...part },
+    { id: '1-part/1-chapter/meta.md', ...chapter },
+    { id: '1-part/1-chapter/1-first/content.md', ...lesson },
+  ]);
+
+  await expect(getTutorial).rejects.toThrowErrorMatchingInlineSnapshot(`[Error: Could not find part '1-part']`);
+});
+
+test('throws when chapter not found', async () => {
+  getCollection.mockReturnValueOnce([
+    { id: 'meta.md', ...tutorial },
+    { id: '1-part/meta.md', ...part },
+    { id: '1-part/2-chapter/meta.md', ...chapter },
+    { id: '1-part/1-chapter/1-first/content.md', ...lesson },
+  ]);
+
+  await expect(getTutorial).rejects.toThrowErrorMatchingInlineSnapshot(`[Error: Could not find chapter '1-chapter']`);
+});
+
+const tutorial: Omit<CollectionEntryTutorial, 'render' | 'id'> = {
+  slug: 'tutorial-slug',
+  body: 'Hello world',
+  collection: 'tutorial',
+  data: { type: 'tutorial' },
+};
+
+const part: Omit<CollectionEntryTutorial, 'render' | 'id'> = {
+  slug: 'part-slug',
+  body: 'Hello world',
+  collection: 'tutorial',
+  data: { type: 'part', title: 'Basics' },
+};
+
+const chapter: Omit<CollectionEntryTutorial, 'render' | 'id'> = {
+  slug: 'chapter-slug',
+  body: 'body here',
+  collection: 'tutorial',
+  data: { title: 'The first chapter in part 1', type: 'chapter' },
+};
+
+const lesson: Omit<CollectionEntryTutorial, 'id'> = {
+  slug: 'lesson-slug',
+  body: 'body here',
+  collection: 'tutorial',
+  data: { type: 'lesson', title: 'Welcome to TutorialKit' },
+  render: () => ({ Content: 'Markdown for tutorial' }) as unknown as ReturnType<CollectionEntryTutorial['render']>,
+};
+
+function snapshotName(ctx: TaskContext) {
+  const testName = ctx.task.name.replaceAll(',', '').replaceAll(' ', '-');
+
+  return `__snapshots__/${testName}.json`;
+}
diff --git a/packages/astro/src/default/utils/content.ts b/packages/astro/src/default/utils/content.ts
index 46e19fe9..b1665ba5 100644
--- a/packages/astro/src/default/utils/content.ts
+++ b/packages/astro/src/default/utils/content.ts
@@ -58,7 +58,7 @@ export async function getTutorial(): Promise<Tutorial> {
       }
 
       if (!_tutorial.parts[partId].chapters[chapterId]) {
-        throw new Error(`Could not find chapter '${partId}'`);
+        throw new Error(`Could not find chapter '${chapterId}'`);
       }
 
       const { Content } = await entry.render();
@@ -321,7 +321,7 @@ function getSlug(entry: CollectionEntryTutorial) {
   return slug;
 }
 
-interface CollectionEntryTutorial {
+export interface CollectionEntryTutorial {
   id: string;
   slug: string;
   body: string;