fix: Throw error when assertion contains only one language chainer (#…

…8105)

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

packages/driver/cypress/integration/commands/assertions_spec.js

@@ -431,6 +431,24 @@ describe('src/cy/commands/assertions', () => {
         cy.noop({}).should('dee.eq', {})
       })
 
+      describe('language chainers err', () => {
+        // https://github.com/cypress-io/cypress/issues/883
+        const langChainers = ['to', 'be', 'been', 'is', 'that', 'which', 'and', 'has', 'have', 'with', 'at', 'of', 'same', 'but', 'does', 'still']
+
+        langChainers.forEach((langChainer) => {
+          it(`throws err when assertion contains only one language chainer: ${langChainer}`, (done) => {
+            cy.on('fail', (err) => {
+              expect(err.message).to.eq(`The chainer \`${langChainer}\` is a language chainer provided to improve the readability of your assertions, not an actual assertion. Please provide a valid assertion.`)
+              expect(err.docsUrl).to.eq('https://on.cypress.io/assertions')
+
+              done()
+            })
+
+            cy.noop(true).should(langChainer, true)
+          })
+        })
+      })
+
       it('throws err when ends with a non available chainable', (done) => {
         cy.on('fail', (err) => {
           expect(err.message).to.eq('The chainer `eq2` was not found. Could not build assertion.')

packages/driver/src/cy/commands/asserting.js

@@ -110,6 +110,14 @@ module.exports = function (Commands, Cypress, cy, state) {
           throwAndLogErr(err)
         }
 
+        // https://github.com/cypress-io/cypress/issues/883
+        // A single chainer used that is not an actual assertion, like '.should('be', 'true')'
+        if (chainers.length < 2 && !_.isFunction(memo[value]) && !isCheckingExistence) {
+          err = $errUtils.cypressErrByPath('should.language_chainer', { args: { originalChainers } })
+          err.retry = false
+          throwAndLogErr(err)
+        }
+
         return applyChainer(memo, value)
       }, exp)
 

packages/driver/src/cypress/error_messages.js

@@ -1361,6 +1361,10 @@ module.exports = {
 
   should: {
     chainer_not_found: 'The chainer `{{chainer}}` was not found. Could not build assertion.',
+    language_chainer: {
+      message: 'The chainer `{{originalChainers}}` is a language chainer provided to improve the readability of your assertions, not an actual assertion. Please provide a valid assertion.',
+      docsUrl: 'https://on.cypress.io/assertions',
+    },
     eventually_deprecated: 'The `eventually` assertion chainer has been deprecated. This is now the default behavior so you can safely remove this word and everything should work as before.',
   },