diff --git a/src/editor/block/format-code.js b/src/editor/block/format-code.js
index f4742dd..23172bc 100644
--- a/src/editor/block/format-code.js
+++ b/src/editor/block/format-code.js
@@ -40,8 +40,8 @@ export const formatBlockContent = async ({ state, dispatch }) => {
                     plugins: language.prettier.plugins,
                     tabWidth: state.tabSize,
                 }),
-                cursorOffset: cursorPos == block.content.from ? 0 : content.length,
             }
+            formattedContent.cursorOffset = cursorPos == block.content.from ? 0 : formattedContent.formatted.length
         } else {
             formattedContent = await prettier.formatWithCursor(content, {
                 cursorOffset: cursorPos - block.content.from,
@@ -62,7 +62,7 @@ export const formatBlockContent = async ({ state, dispatch }) => {
             to: block.content.to,
             insert: formattedContent.formatted,
         },
-        selection: EditorSelection.cursor(block.content.from + formattedContent.cursorOffset),
+        selection: EditorSelection.cursor(block.content.from + Math.min(formattedContent.cursorOffset, formattedContent.formatted.length)),
     }, {
         userEvent: "input",
         scrollIntoView: true,
diff --git a/tests/formatting.spec.js b/tests/formatting.spec.js
new file mode 100644
index 0000000..76d91ae
--- /dev/null
+++ b/tests/formatting.spec.js
@@ -0,0 +1,46 @@
+import { test, expect } from "@playwright/test";
+import { HeynotePage } from "./test-utils.js";
+
+let heynotePage
+
+test.beforeEach(async ({ page }) => {
+    console.log("beforeEach")
+    heynotePage = new HeynotePage(page)
+    await heynotePage.goto()
+})
+
+
+test("JSON formatting", async ({ page }) => {
+    heynotePage.setContent(`
+∞∞∞json
+    {"test": 1, "key2": "hey!"}
+`)
+    expect(await page.locator("css=.status .status-block.lang")).toHaveText("JSON")
+    await page.locator("css=.status-block.format").click()
+    await page.waitForTimeout(100)
+    expect(await heynotePage.getBlockContent(0)).toBe(`{
+    "test": 1,
+    "key2": "hey!"
+}
+`)
+})
+
+test("JSON formatting (cursor at start)", async ({ page }) => {
+    heynotePage.setContent(`
+∞∞∞json
+    {"test": 1, "key2": "hey!"}
+`)
+    expect(await page.locator("css=.status .status-block.lang")).toHaveText("JSON")
+    for (let i=0; i<5; i++) {
+        await page.locator("body").press("ArrowUp")
+    }
+    await page.locator("css=.status-block.format").click()
+    await page.waitForTimeout(100)
+    expect(await heynotePage.getBlockContent(0)).toBe(`{
+    "test": 1,
+    "key2": "hey!"
+}
+`)
+    const block = (await heynotePage.getBlocks())[0]
+    expect(await page.evaluate(() => window._heynote_editor.view.state.selection.main.from)).toBe(block.content.from)
+})
\ No newline at end of file
diff --git a/tests/language-detection.spec.js b/tests/language-detection.spec.js
new file mode 100644
index 0000000..6581623
--- /dev/null
+++ b/tests/language-detection.spec.js
@@ -0,0 +1,41 @@
+import { test, expect } from "@playwright/test";
+import { HeynotePage } from "./test-utils.js";
+
+let heynotePage
+
+test.beforeEach(async ({ page }) => {
+    console.log("beforeEach")
+    heynotePage = new HeynotePage(page)
+    await heynotePage.goto()
+})
+
+
+test("test valid JSON detection", async ({ page }) => {
+    page.locator("body").pressSequentially(`
+        {"test": 1, "key2": "hey!"}
+    `)
+    await page.waitForTimeout(200);
+    expect(await page.locator("css=.status .status-block.lang")).toHaveText("JSON (auto)")
+    const block = (await heynotePage.getBlocks())[0]
+    expect(block.language.name).toBe("json")
+    expect(block.language.auto).toBeTruthy()
+})
+
+
+test("python detection", async ({ page }) => {
+    page.locator("body").pressSequentially(`
+# import complex math module
+import cmath
+
+# calculate the discriminant
+d = (b**2) - (4*a*c)
+
+# find two solutions
+sol1 = (-b-cmath.sqrt(d))/(2*a)
+sol2 = (-b+cmath.sqrt(d))/(2*a)
+
+print('The solution are {0} and {1}'.format(sol1,sol2))
+    `)
+    await page.waitForTimeout(1000);
+    expect(await page.locator("css=.status .status-block.lang")).toHaveText("Python (auto)")
+})
diff --git a/tests/test-utils.js b/tests/test-utils.js
index 005694c..4ef6fe7 100644
--- a/tests/test-utils.js
+++ b/tests/test-utils.js
@@ -29,7 +29,7 @@ export class HeynotePage {
     async getContent() {
         return await this.page.evaluate(() => window._heynote_editor.getContent())
     }
-    
+
     async setContent(content) {
         await this.page.evaluate((content) => window._heynote_editor.setContent(content), content)
     }