feat: add isOn function

You can check the condition against a browser name or an environment
yourself.

```js
import {isOn} from '@cypress/skip-test'
it('loads users', () => {
  // when running on Windows locally, the backend is not running
  // thus we need to stub XHR requests
  if (isOn('windows') && isOn('localhost')) {
    cy.server()
    cy.route('/users', 'fixture:users')
  }
  cy.visit('/')
  cy.get('.user').should('have.length', 10)
})
```

README.md

@@ -148,6 +148,24 @@ it.only('runs if task returns production', () => {
 })
 ```
 
+### `isOn`
+
+You can check the condition against a browser name or an environment yourself.
+
+```js
+import {isOn} from '@cypress/skip-test'
+it('loads users', () => {
+  // when running on Windows locally, the backend is not running
+  // thus we need to stub XHR requests
+  if (isOn('windows') && isOn('localhost')) {
+    cy.server()
+    cy.route('/users', 'fixture:users')
+  }
+  cy.visit('/')
+  cy.get('.user').should('have.length', 10)
+})
+```
+
 ### Notes
 
 You can chain conditions together

cypress/integration/is-on-spec.js

@@ -0,0 +1,17 @@
+/// <reference types="cypress" />
+import { isOn } from '../..'
+
+it('returns true for current browser', () => {
+  expect(isOn(Cypress.browser.name)).to.be.true
+})
+
+it('returns true for current platform', () => {
+  expect(isOn(Cypress.platform)).to.be.true
+})
+
+it('returns true for current url', () => {
+  const url = Cypress.config('baseUrl')
+  expect(url).to.be.a('string')
+  expect(isOn(url)).to.be.true
+  expect(isOn('foo.com')).to.be.false
+})

cypress/integration/nested-spec.js

@@ -7,3 +7,9 @@ onlyOn('mac', () => {
     it('works', () => {})
   })
 })
+
+onlyOn('mac', () => {
+  onlyOn('electron', () => {
+    it('runs on Mac Electron', () => {})
+  })
+})

index.js

@@ -26,6 +26,30 @@ const normalizeName = name => {
   return normalizedName
 }
 
+/**
+ * Returns true if the test is running on the given browser or platform
+ * or against given url.
+ * @param {string} name Browser name, platform or url.
+ * @returns {boolean} Returns true if the test runs against the given condition.
+ */
+const isOn = name => {
+  if (!_.isString(name)) {
+    throw new Error('Invalid syntax: isOn expects a string argument')
+  }
+
+  const normalizedName = normalizeName(name)
+
+  if (isPlatform(normalizedName)) {
+    return Cypress.platform === normalizedName
+  }
+
+  if (isBrowser(normalizedName)) {
+    return Cypress.browser.name === normalizedName
+  }
+
+  return matchesUrlPart(normalizedName)
+}
+
 const getMochaContext = () => cy.state('runnable').ctx
 const skip = () => {
   const ctx = getMochaContext()
@@ -75,11 +99,6 @@ const skipOn = (name, cb) => {
     )
   }
 
-  const skip = () => {
-    const ctx = getMochaContext()
-    return ctx.skip()
-  }
-
   const normalizedName = normalizeName(name)
 
   if (cb) {
@@ -159,44 +178,21 @@ const onlyOn = (name, cb) => {
     )
   }
 
-  const normalizedName = normalizeName(name)
-
   if (cb) {
-    if (isPlatform(normalizedName) && Cypress.platform === normalizedName) {
-      return cb()
-    }
-
-    if (isBrowser(normalizedName) && Cypress.browser.name === normalizedName) {
-      return cb()
-    }
-
-    if (matchesUrlPart(normalizedName)) {
+    if (isOn(name)) {
       return cb()
     }
   } else {
+    const normalizedName = normalizeName(name)
     cy.log(`onlyOn **${normalizedName}**`)
-
-    if (isPlatform(normalizedName)) {
-      if (Cypress.platform !== normalizedName) {
-        skip()
-      }
-      return
-    }
-
-    if (isBrowser(normalizedName)) {
-      if (Cypress.browser.name !== normalizedName) {
-        skip()
-      }
-      return
-    }
-
-    if (!matchesUrlPart(normalizedName)) {
+    if (!isOn(name)) {
       return skip()
     }
   }
 }
 
 module.exports = {
   skipOn,
-  onlyOn
+  onlyOn,
+  isOn
 }