fix: retain original array after defaultsDeep #27240 (#27312)

* modifying object after array combination to hold older values

* regression test

* made suggested changes

* config defaults

* log

* logs

* log

* log again

* update log

* changelog

* updates changelog

* fix typo and move changelog entry and fix link

---------

Co-authored-by: Nihar Phansalkar <phansalkarnihar@gmail.com>
Co-authored-by: Jennifer Shehane <jennifer@cypress.io>
Co-authored-by: Cacie Prins <cacieprins@users.noreply.github.com>
Co-authored-by: Cacie Prins <cacie@cypress.io>
Co-authored-by: AtofStryker <bglesias@gmail.com>

cli/CHANGELOG.md

@@ -1,4 +1,12 @@
 <!-- See the ../guides/writing-the-cypress-changelog.md for details on writing the changelog. -->
+## 13.7.2
+
+_Released 4/2/2024 (PENDING)_
+
+**Bugfixes:**
+
+- Fixed a bug where fields using arrays in `cypress.config` are not correctly processed. Fixes [#27103](https://github.com/cypress-io/cypress/issues/27103). Fixed in [#27312](https://github.com/cypress-io/cypress/pull/27312).
+
 ## 13.7.1
 
 _Released 3/21/2024_

packages/app/cypress/e2e/subscriptions/specChange-subscription.cy.ts

@@ -444,6 +444,40 @@ e2e: {
 
       cy.get('[data-cy="file-match-indicator"]', { timeout: 7500 })
       .should('contain', '3 matches')
+
+      // Regression for https://github.com/cypress-io/cypress/issues/27103
+      cy.withCtx(async (ctx) => {
+        await ctx.actions.file.writeFileInProject('cypress.config.js',
+`   
+module.exports = {
+  projectId: 'abc123',
+  experimentalInteractiveRunEvents: true,
+  component: {
+    specPattern: 'src/**/*.{spec,cy}.{js,jsx,ts,tsx}',
+    supportFile: false,
+    devServer: {
+      framework: 'react',
+      bundler: 'webpack',
+    }
+  },
+  e2e: {
+    specPattern: ['cypress/e2e/**/dom-cont*.spec.{js,ts}'],
+    supportFile: false,
+    setupNodeEvents(on, config) {
+      /**
+       * This should make Cypress yield a "no specs found" error.
+       *
+       * This stops being the case if 'specPattern' is an array.
+       */
+      config.specPattern = [];
+      return config;
+    },
+  },
+}`)
+      })
+
+      cy.get('[data-cy="create-spec-page-title"]')
+      .should('contain', defaultMessages.createSpec.page.customPatternNoSpecs.title)
     })
   })
 })

packages/config/src/project/index.ts

@@ -105,8 +105,16 @@ export function updateWithPluginValues (cfg: FullConfig, modifiedConfig: any, te
     debug('resolved config object %o', cfg.resolved)
   }
 
+  const diffsClone = _.cloneDeep(diffs) ?? {}
+
   // merge cfg into overrides
-  const merged = _.defaultsDeep(diffs, cfg)
+  const merged = _.defaultsDeep(diffs, cfg) ?? {}
+
+  for (const [key, value] of Object.entries(diffsClone)) {
+    if (Array.isArray(value)) {
+      merged[key] = _.cloneDeep(value)
+    }
+  }
 
   debug('merged config object %o', merged)