fix: return raw fixture when encoding is specified (#32155)

* fix: return raw fixture when encoding is specified

* revert: revert test change

---------

Co-authored-by: Jennifer Shehane <[email protected]>
Co-authored-by: Bill Glesias <[email protected]>

Author: 3 people

cli/CHANGELOG.md

@@ -7,6 +7,7 @@ _Released 8/12/2025 (PENDING)_
 
 - Fixed an issue where Angular legacy `Output()` decorators were broken when making component instance field references safe. Fixes [#32137](https://github.com/cypress-io/cypress/issues/32137).
 - Upgraded `tmp` from `~0.2.3` to `~0.2.4`. This removes the [CVE-2025-54798](https://github.com/advisories/GHSA-52f5-9888-hmc6) vulnerability being reported in security scans. Addresses [#32176](https://github.com/cypress-io/cypress/issues/32176).
+- Fixed an issue where `.fixture()` calls with a specified encoding would sometimes still attempt to parse the file based on its extension. Files with an explicit encoding are now always treated as raw content. Fixes [#32139](https://github.com/cypress-io/cypress/issues/32139).
 - Fixed an issue where `.fixture()` calls with different encoding options would return inconsistent content based on execution order. Fixes [#32138](https://github.com/cypress-io/cypress/issues/32138).
 
 ## 14.5.4

packages/server/lib/fixture.js

@@ -125,13 +125,10 @@ module.exports = {
   },
 
   parseFileByExtension (p, fixture, ext, options = {}) {
-    // https://github.com/cypress-io/cypress/issues/1558
-    // If the user explicitly specifies `null` as the encoding, we treat the
-    // file as binary regardless of extension. We base64 encode them for
-    // transmission over the websocket. There is a matching Buffer.from()
-    // in packages/driver/src/cy/commands/fixtures.ts
-    if (options.encoding === null) {
-      return this.parse(p, fixture)
+    // If an encoding is specified, return the raw file content instead of
+    // parsing.
+    if (typeof options.encoding !== 'undefined') {
+      return this.parse(p, fixture, options.encoding)
     }
 
     switch (ext) {

packages/server/test/unit/fixture_spec.js

@@ -169,6 +169,22 @@ describe('lib/fixture', () => {
         })
       })
     })
+
+    it('should return encoded JSON', async function () {
+      const fixtures = [
+        { encoding: '', content: Buffer.from('[{"json": true}]') },
+        { encoding: 'base64', content: 'W3sianNvbiI6IHRydWV9XQ==' },
+        { encoding: 'utf8', content: '[{"json": true}]' },
+        { encoding: null, content: Buffer.from('[{"json": true}]') },
+        { encoding: undefined, content: [{ json: true }] },
+      ]
+
+      for (const { encoding, content } of fixtures) {
+        const result = await fixture.get(this.fixturesFolder, 'foo', { encoding })
+
+        expect(result).to.deep.equal(content)
+      }
+    })
   })
 
   context('js files', () => {