fix(snapshot): reject multiple toMatchInlineSnapshot updates at the…

… same location (#6332)

packages/snapshot/src/port/state.ts

@@ -158,6 +158,13 @@ export default class SnapshotState {
       // location for js files, but `column-1` points to the same in both js/ts
       // https://github.com/vitejs/vite/issues/8657
       stack.column--
+      // reject multiple inline snapshots at the same location
+      const duplicateIndex = this._inlineSnapshots.findIndex(s => s.file === stack.file && s.line === stack.line && s.column === stack.column)
+      if (duplicateIndex >= 0) {
+        // remove the first one to avoid updating an inline snapshot
+        this._inlineSnapshots.splice(duplicateIndex, 1)
+        throw new Error('toMatchInlineSnapshot cannot be called multiple times at the same location.')
+      }
       this._inlineSnapshots.push({
         snapshot: receivedSerialized,
         ...stack,

test/cli/fixtures/fails/inline-snapshop-inside-loop-update-all.test.ts

@@ -0,0 +1,23 @@
+import {test, expect} from "vitest";
+
+test("ok", () => {
+  expect("ok").toMatchInlineSnapshot(`"ok"`);
+});
+
+test("fail 1", () => {
+  for (const str of ["foo", "bar"]) {
+    expect(str).toMatchInlineSnapshot();
+  }
+});
+
+test("fail 3", () => {
+  for (const str of ["ok", "ok"]) {
+    expect(str).toMatchInlineSnapshot();
+  }
+});
+
+test("somehow ok", () => {
+  for (const str of ["ok", "ok"]) {
+    expect(str).toMatchInlineSnapshot(`"ok"`);
+  }
+});

test/cli/fixtures/fails/inline-snapshop-inside-loop-update-none.test.ts

@@ -0,0 +1,9 @@
+import {test, expect} from "vitest";
+
+// this test causes infinite re-run when --watch and --update
+// since snapshot update switches between "foo" and "bar" forever.
+test("fail 2", () => {
+  for (const str of ["foo", "bar"]) {
+    expect(str).toMatchInlineSnapshot(`"bar"`);
+  }
+});

test/cli/test/__snapshots__/fails.test.ts.snap

@@ -31,6 +31,13 @@ Error: InlineSnapshot cannot be used inside of test.each or describe.each
 Error: InlineSnapshot cannot be used inside of test.each or describe.each"
 `;
 
+exports[`should fail inline-snapshop-inside-loop-update-all.test.ts > inline-snapshop-inside-loop-update-all.test.ts 1`] = `
+"Error: toMatchInlineSnapshot cannot be called multiple times at the same location.
+Error: toMatchInlineSnapshot cannot be called multiple times at the same location."
+`;
+
+exports[`should fail inline-snapshop-inside-loop-update-none.test.ts > inline-snapshop-inside-loop-update-none.test.ts 1`] = `"Error: Snapshot \`fail 2 1\` mismatched"`;
+
 exports[`should fail mock-import-proxy-module.test.ts > mock-import-proxy-module.test.ts 1`] = `"Error: There are some problems in resolving the mocks API."`;
 
 exports[`should fail nested-suite.test.ts > nested-suite.test.ts 1`] = `"AssertionError: expected true to be false // Object.is equality"`;

test/cli/test/fails.test.ts

@@ -8,7 +8,10 @@ const root = resolve(__dirname, '../fixtures/fails')
 const files = await fg('**/*.test.ts', { cwd: root, dot: true })
 
 it.each(files)('should fail %s', async (file) => {
-  const { stderr } = await runVitest({ root }, [file])
+  const { stderr } = await runVitest({
+    root,
+    update: file === 'inline-snapshop-inside-loop-update-all.test.ts' ? true : undefined,
+  }, [file])
 
   expect(stderr).toBeTruthy()
   const msg = String(stderr)