From 96e26811dac63ecc77b2f17d1243144a1bb63cca Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nlawson@salesforce.com>
Date: Mon, 2 Dec 2024 10:56:51 -0800
Subject: [PATCH 1/3] fix(ssr): adjacent text in `<template>`s

Co-Authored-By: Will Harney <62956339+wjhsf@users.noreply.github.com>
Co-Authored-By: John Hefferman <jhefferman@salesforce.com>
---
 .../deep-for-each-with-rendered-item/error.txt           | 0
 .../deep-for-each-with-rendered-item/expected.html       | 9 +++++++++
 .../deep-for-each-with-rendered-item/index.js            | 3 +++
 .../modules/x/comments-text/comments-text.html           | 9 +++++++++
 .../modules/x/comments-text/comments-text.js             | 5 +++++
 .../preserve-comments-off/deep-for-each/error.txt        | 0
 .../preserve-comments-off/deep-for-each/expected.html    | 9 +++++++++
 .../preserve-comments-off/deep-for-each/index.js         | 3 +++
 .../modules/x/comments-text/comments-text.html           | 9 +++++++++
 .../modules/x/comments-text/comments-text.js             | 5 +++++
 .../preserve-comments-off/deep-iterator/error.txt        | 0
 .../preserve-comments-off/deep-iterator/expected.html    | 9 +++++++++
 .../preserve-comments-off/deep-iterator/index.js         | 3 +++
 .../modules/x/comments-text/comments-text.html           | 9 +++++++++
 .../modules/x/comments-text/comments-text.js             | 5 +++++
 .../src/__tests__/utils/expected-failures.ts             | 2 +-
 .../src/compile-template/transformers/for-each.ts        | 6 ++----
 .../src/compile-template/transformers/for-of.ts          | 6 ++----
 .../ssr-compiler/src/compile-template/transformers/if.ts | 4 ++--
 19 files changed, 85 insertions(+), 11 deletions(-)
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/error.txt
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/expected.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/index.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/error.txt
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/expected.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/index.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/error.txt
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/expected.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/index.js
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.html
 create mode 100644 packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.js

diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/error.txt b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/error.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/expected.html
new file mode 100644
index 0000000000..e512105443
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/expected.html
@@ -0,0 +1,9 @@
+<x-comments-text>
+  <template shadowrootmode="open">
+    ab
+    <div data-foo="1">
+      c
+    </div>
+    de
+  </template>
+</x-comments-text>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/index.js b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/index.js
new file mode 100644
index 0000000000..4bd94488e9
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/index.js
@@ -0,0 +1,3 @@
+export const tagName = 'x-comments-text';
+export { default } from 'x/comments-text';
+export * from 'x/comments-text';
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.html b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.html
new file mode 100644
index 0000000000..0f2b87f576
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.html
@@ -0,0 +1,9 @@
+<template>
+    a
+    <template for:each={items} for:item="item">
+        b
+        <div key={item} data-foo={item}>c</div>
+        d
+    </template>
+    e
+</template>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.js b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.js
new file mode 100644
index 0000000000..a8ae62d4cd
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/modules/x/comments-text/comments-text.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    items = [1];
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/error.txt b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/error.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/expected.html
new file mode 100644
index 0000000000..841e1096c3
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/expected.html
@@ -0,0 +1,9 @@
+<x-comments-text>
+  <template shadowrootmode="open">
+    ab
+    <div>
+      c
+    </div>
+    de
+  </template>
+</x-comments-text>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/index.js b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/index.js
new file mode 100644
index 0000000000..4bd94488e9
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/index.js
@@ -0,0 +1,3 @@
+export const tagName = 'x-comments-text';
+export { default } from 'x/comments-text';
+export * from 'x/comments-text';
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.html b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.html
new file mode 100644
index 0000000000..86d2e3c797
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.html
@@ -0,0 +1,9 @@
+<template>
+    a
+    <template for:each={items} for:item="item">
+        b
+        <div key={item}>c</div>
+        d
+    </template>
+    e
+</template>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.js b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.js
new file mode 100644
index 0000000000..a8ae62d4cd
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-for-each/modules/x/comments-text/comments-text.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    items = [1];
+}
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/error.txt b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/error.txt
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/expected.html b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/expected.html
new file mode 100644
index 0000000000..841e1096c3
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/expected.html
@@ -0,0 +1,9 @@
+<x-comments-text>
+  <template shadowrootmode="open">
+    ab
+    <div>
+      c
+    </div>
+    de
+  </template>
+</x-comments-text>
\ No newline at end of file
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/index.js b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/index.js
new file mode 100644
index 0000000000..4bd94488e9
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/index.js
@@ -0,0 +1,3 @@
+export const tagName = 'x-comments-text';
+export { default } from 'x/comments-text';
+export * from 'x/comments-text';
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.html b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.html
new file mode 100644
index 0000000000..02b7645ce7
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.html
@@ -0,0 +1,9 @@
+<template>
+    a
+    <template iterator:it={items}>
+        b
+        <div key={it.value}>c</div>
+        d
+    </template>
+    e
+</template>
diff --git a/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.js b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.js
new file mode 100644
index 0000000000..a8ae62d4cd
--- /dev/null
+++ b/packages/@lwc/engine-server/src/__tests__/fixtures/adjacent-text-nodes/preserve-comments-off/deep-iterator/modules/x/comments-text/comments-text.js
@@ -0,0 +1,5 @@
+import { LightningElement } from 'lwc';
+
+export default class extends LightningElement {
+    items = [1];
+}
diff --git a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
index 97b5f1d186..ae97a197e3 100644
--- a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
+++ b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
@@ -8,7 +8,7 @@
 // We should slowly drive down these test failures or at least document where we expect the failures
 // TODO [#4815]: enable all SSR v2 tests
 export const expectedFailures = new Set([
-    'adjacent-text-nodes/preserve-comments-off/deep2/index.js',
+    'adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item',
     'attribute-aria/dynamic/index.js',
     'attribute-class/with-scoped-styles-only-in-child/dynamic/index.js',
     'attribute-class/with-scoped-styles/dynamic/index.js',
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-each.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-each.ts
index 9d496876f9..a4b3d53e2a 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-each.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-each.ts
@@ -7,7 +7,7 @@
 
 import { builders as b, is } from 'estree-toolkit';
 import { esTemplate } from '../../estemplate';
-import { irToEs } from '../ir-to-es';
+import { irChildrenToEs } from '../ir-to-es';
 import { getScopedExpression, optimizeAdjacentYieldStmts } from '../shared';
 
 import type { ForEach as IrForEach } from '@lwc/template-compiler';
@@ -25,9 +25,7 @@ export const ForEach: Transformer<IrForEach> = function ForEach(node, cxt): EsFo
     const forIndexId = node.index?.name ?? '__unused__';
 
     cxt.pushLocalVars([forItemId, forIndexId]);
-    const forEachStatements = node.children.flatMap((childNode) => {
-        return irToEs(childNode, cxt);
-    });
+    const forEachStatements = irChildrenToEs(node.children, cxt);
     cxt.popLocalVars();
 
     const expression = node.expression as EsExpression;
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-of.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-of.ts
index e9eac621a7..dea800f1fd 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-of.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/for-of.ts
@@ -7,7 +7,7 @@
 
 import { builders as b, is } from 'estree-toolkit';
 import { esTemplate } from '../../estemplate';
-import { irToEs } from '../ir-to-es';
+import { irChildrenToEs } from '../ir-to-es';
 import { optimizeAdjacentYieldStmts } from '../shared';
 
 import type { ForOf as IrForOf } from '@lwc/template-compiler';
@@ -37,9 +37,7 @@ const bForOfYieldFrom = esTemplate`
 export const ForOf: Transformer<IrForOf> = function ForEach(node, cxt): EsForOfStatement[] {
     const id = node.iterator.name;
     cxt.pushLocalVars([id]);
-    const forEachStatements = node.children.flatMap((childNode) => {
-        return irToEs(childNode, cxt);
-    });
+    const forEachStatements = irChildrenToEs(node.children, cxt);
     cxt.popLocalVars();
 
     const expression = node.expression as EsExpression;
diff --git a/packages/@lwc/ssr-compiler/src/compile-template/transformers/if.ts b/packages/@lwc/ssr-compiler/src/compile-template/transformers/if.ts
index ae62c7cc8e..8da2b06fa9 100644
--- a/packages/@lwc/ssr-compiler/src/compile-template/transformers/if.ts
+++ b/packages/@lwc/ssr-compiler/src/compile-template/transformers/if.ts
@@ -6,7 +6,7 @@
  */
 
 import { builders as b } from 'estree-toolkit';
-import { irToEs } from '../ir-to-es';
+import { irChildrenToEs } from '../ir-to-es';
 import { expressionIrToEs } from '../expression';
 import { optimizeAdjacentYieldStmts } from '../shared';
 
@@ -28,7 +28,7 @@ function bBlockStatement(
     cxt: TransformerContext,
     insertComments: boolean
 ): EsBlockStatement {
-    let statements = childNodes.flatMap((childNode) => irToEs(childNode, cxt));
+    let statements = irChildrenToEs(childNodes, cxt);
     if (insertComments) statements = [bYieldComment(), ...statements, bYieldComment()];
     return b.blockStatement(optimizeAdjacentYieldStmts(statements));
 }

From 29c42fba58101bbc5b6994c30d7942c7d3a0cc46 Mon Sep 17 00:00:00 2001
From: Nolan Lawson <nlawson@salesforce.com>
Date: Mon, 2 Dec 2024 11:02:57 -0800
Subject: [PATCH 2/3] test: fix expected failures

---
 .../@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
index ae97a197e3..ac48a15efe 100644
--- a/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
+++ b/packages/@lwc/ssr-compiler/src/__tests__/utils/expected-failures.ts
@@ -8,7 +8,7 @@
 // We should slowly drive down these test failures or at least document where we expect the failures
 // TODO [#4815]: enable all SSR v2 tests
 export const expectedFailures = new Set([
-    'adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item',
+    'adjacent-text-nodes/preserve-comments-off/deep-for-each-with-rendered-item/index.js',
     'attribute-aria/dynamic/index.js',
     'attribute-class/with-scoped-styles-only-in-child/dynamic/index.js',
     'attribute-class/with-scoped-styles/dynamic/index.js',
@@ -30,7 +30,6 @@ export const expectedFailures = new Set([
     'scoped-slots/mixed-with-light-dom-slots-inside/index.js',
     'scoped-slots/mixed-with-light-dom-slots-outside/index.js',
     'slot-forwarding/scoped-slots/index.js',
-    'slot-not-at-top-level/advanced/ifTrue/light/index.js',
     'slot-not-at-top-level/advanced/ifTrue/shadow/index.js',
     'slot-not-at-top-level/advanced/lwcIf/light/index.js',
     'slot-not-at-top-level/advanced/lwcIf/shadow/index.js',

From 846235e1e1f2576d287f09813a3748170c915041 Mon Sep 17 00:00:00 2001
From: Will Harney <wharney@salesforce.com>
Date: Mon, 2 Dec 2024 14:43:11 -0500
Subject: [PATCH 3/3] test(snapshots): add helpfuler message when
 error/expected swap

---
 scripts/test-utils/test-fixture-dir.ts | 54 +++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/scripts/test-utils/test-fixture-dir.ts b/scripts/test-utils/test-fixture-dir.ts
index 7da24fd186..c362d73721 100644
--- a/scripts/test-utils/test-fixture-dir.ts
+++ b/scripts/test-utils/test-fixture-dir.ts
@@ -5,8 +5,9 @@
  * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT
  */
 
-import fs from 'node:fs';
+import fs, { readFileSync } from 'node:fs';
 import path from 'node:path';
+import { AssertionError } from 'node:assert';
 import { test } from 'vitest';
 import * as glob from 'glob';
 import type { Config as StyleCompilerConfig } from '@lwc/style-compiler';
@@ -145,7 +146,9 @@ export function testFixtureDir<T extends TestFixtureConfig>(
                 );
             }
 
-            for (const [outputName, content] of Object.entries(outputs)) {
+            const outputsList = Object.entries(outputs);
+
+            for (const [outputName, content] of outputsList) {
                 const outputPath = path.resolve(dirname, outputName);
                 try {
                     await expect(content ?? '').toMatchFileSnapshot(outputPath);
@@ -156,6 +159,53 @@ export function testFixtureDir<T extends TestFixtureConfig>(
                         Error.captureStackTrace(err, testFixtureDir);
                     }
 
+                    const isErrorSnapshot = outputName.startsWith('error');
+                    const isSuccessSnapshot = outputName.startsWith('expected');
+
+                    // If we change from a successful result to an error (or vice versa),
+                    // then either the snapshot or content for the failing file is empty,
+                    // and the diff printed in the error message isn't helpful. Here, we check for
+                    // that case, and then check if the other file has flipped the other way.
+                    // If it has, we throw a more helpful error message.
+                    if (isErrorSnapshot || isSuccessSnapshot) {
+                        const brokenResult = outputs[outputName];
+                        const brokenResultHasContent = Boolean(brokenResult);
+                        const brokenSnapshot = readFileSync(outputPath, 'utf8');
+                        const brokenSnapshotHasContent = Boolean(brokenSnapshot);
+                        if (brokenResultHasContent !== brokenSnapshotHasContent) {
+                            // This file flipped from content to empty, or vice versa
+                            const otherType = isErrorSnapshot ? 'expected' : 'error';
+                            const otherName = outputsList.find(([name]) =>
+                                name.startsWith(otherType)
+                            )![0];
+                            const otherResult = outputs[otherName];
+                            const otherResultHasContent = Boolean(otherResult);
+                            const otherSnapshot = readFileSync(
+                                path.resolve(dirname, otherName),
+                                'utf8'
+                            );
+                            const otherSnapshotHasContent = Boolean(otherSnapshot);
+                            if (otherResultHasContent !== otherSnapshotHasContent) {
+                                // The other file has flipped from content to empty, or vice versa
+                                const expectedContentName = brokenSnapshotHasContent
+                                    ? outputName
+                                    : otherName;
+                                const actualContentName = brokenResultHasContent
+                                    ? outputName
+                                    : otherName;
+                                const contentErr = new AssertionError({
+                                    message: `Expected content in ${expectedContentName}, but found content in ${actualContentName}.`,
+                                    expected: brokenSnapshotHasContent
+                                        ? brokenSnapshot
+                                        : otherSnapshot,
+                                    actual: brokenResultHasContent ? brokenResult : otherResult,
+                                });
+                                Error.captureStackTrace(contentErr, testFixtureDir);
+                                throw contentErr;
+                            }
+                        }
+                    }
+
                     throw err;
                 }
             }