fix(pretty-format): print ArrayBuffer and DataView correctly (#14290)

jestjs · Sep 20, 2023 · c13c649 · c13c649
1 parent 571b230
commit c13c649
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Showing 3 changed files with 22 additions and 7 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -14,6 +14,7 @@
 
 - `[babel-plugin-jest-hoist]` Use `denylist` instead of the deprecated `blacklist` for Babel 8 support ([#14109](https://github.com/jestjs/jest/pull/14109))
 - `[jest-leak-detector]` Make leak-detector more aggressive when running GC ([#14526](https://github.com/jestjs/jest/pull/14526))
+- `[pretty-format]` [**BREAKING**] Print `ArrayBuffer` and `DataView` correctly ([#14290](https://github.com/facebook/jest/pull/14290))
 
 ### Performance
 

diff --git a/packages/pretty-format/src/__tests__/prettyFormat.test.ts b/packages/pretty-format/src/__tests__/prettyFormat.test.ts
@@ -79,7 +79,12 @@ describe('prettyFormat()', () => {
 
   it('prints an array buffer', () => {
     const val = new ArrayBuffer(3);
-    expect(prettyFormat(val)).toBe('ArrayBuffer []');
+    expect(prettyFormat(val)).toBe('ArrayBuffer [\n  0,\n  0,\n  0,\n]');
+  });
+
+  it('prints an data view', () => {
+    const val = new DataView(new ArrayBuffer(3));
+    expect(prettyFormat(val)).toBe('DataView [\n  0,\n  0,\n  0,\n]');
   });
 
   it('prints a nested array', () => {

diff --git a/packages/pretty-format/src/collections.ts b/packages/pretty-format/src/collections.ts
@@ -146,33 +146,42 @@ export function printIteratorValues(
  * without surrounding punctuation (for example, brackets)
  **/
 export function printListItems(
-  list: ArrayLike<unknown>,
+  list: ArrayLike<unknown> | DataView | ArrayBuffer,
   config: Config,
   indentation: string,
   depth: number,
   refs: Refs,
   printer: Printer,
 ): string {
   let result = '';
+  list = list instanceof ArrayBuffer ? new DataView(list) : list;
+  const isDataView = (l: unknown): l is DataView => l instanceof DataView;
+  const length = isDataView(list) ? list.byteLength : list.length;
 
-  if (list.length > 0) {
+  if (length > 0) {
     result += config.spacingOuter;
 
     const indentationNext = indentation + config.indent;
 
-    for (let i = 0; i < list.length; i++) {
+    for (let i = 0; i < length; i++) {
       result += indentationNext;
 
       if (i === config.maxWidth) {
         result += '…';
         break;
       }
 
-      if (i in list) {
-        result += printer(list[i], config, indentationNext, depth, refs);
+      if (isDataView(list) || i in list) {
+        result += printer(
+          isDataView(list) ? list.getInt8(i) : list[i],
+          config,
+          indentationNext,
+          depth,
+          refs,
+        );
       }
 
-      if (i < list.length - 1) {
+      if (i < length - 1) {
         result += `,${config.spacingInner}`;
       } else if (!config.min) {
         result += ',';