feat: add explicit check against codeCoverage.expectFrontendCoverageOnly before attempting to collect backend coverage (#555)

Co-authored-by: Jennifer Shehane <jennifer@cypress.io>
Co-authored-by: AtofStryker <bglesias@gmail.com>

Author: 3 people

README.md

@@ -251,6 +251,21 @@ After:
 
 ![Cypress knows to expect the backend code coverage only](./images/expect-backend.png)
 
+### expectFrontendCoverageOnly
+
+If there is ONLY frontend code coverage, set `expectFrontendCoverageOnly: true` in the `cypress.json` file. Otherwise, Cypress complains that it cannot find the frontend code coverage.
+
+```json
+{
+  "env": {
+    "codeCoverage": {
+      "url": "http://localhost:3003/__coverage__",
+      "expectFrontendCoverageOnly": true
+    }
+  }
+}
+```
+
 ## Custom report folder
 
 You can specify a custom report folder by adding `nyc` object to the `package.json` file. For example, to save reports to `cypress-coverage` folder, use:

support.js

@@ -178,10 +178,19 @@ const registerHooks = () => {
     const baseUrl = Cypress.config('baseUrl') || cy.state('window').origin
     // @ts-ignore
     const runningEndToEndTests = baseUrl !== Cypress.config('proxyUrl')
+    const expectFrontendCoverageOnly = Cypress._.get(
+      Cypress.env('codeCoverage'),
+      'expectFrontendCoverageOnly',
+      false
+    )
     const specType = Cypress._.get(Cypress.spec, 'specType', 'integration')
     const isIntegrationSpec = specType === 'integration'
 
-    if (runningEndToEndTests && isIntegrationSpec) {
+    if (
+      !expectFrontendCoverageOnly &&
+      runningEndToEndTests &&
+      isIntegrationSpec
+    ) {
       // we can only request server-side code coverage
       // if we are running end-to-end tests,
       // otherwise where do we send the request?