fix: run an empty spec if there are no specs for this machine, closes #6

cypress/e2e/chunks.cy.js

@@ -29,8 +29,9 @@ describe('getChunk', () => {
     const specs = [1]
     let chunk = getChunk(specs, 2, 0)
     expect(chunk, 'chunk 0').to.deep.equal([1])
+    // nothing to do in the second machine
     chunk = getChunk(specs, 2, 1)
-    expect(chunk, 'chunk 1').to.deep.equal(undefined)
+    expect(chunk, 'chunk 1').to.deep.equal([])
   })
 })
 

package.json

@@ -9,7 +9,8 @@
   "scripts": {
     "test": "cypress run",
     "badges": "npx -p dependency-version-badge update-badge cypress",
-    "semantic-release": "semantic-release"
+    "semantic-release": "semantic-release",
+    "empty": "DEBUG=cypress-split SPLIT=10 SPLIT_INDEX=9 cypress run"
   },
   "repository": {
     "type": "git",

src/chunk.js

@@ -32,6 +32,11 @@ function chunkify(a, n, balanced) {
   return out
 }
 
+/**
+ * Splits the given array across N "buckets"
+ * and returns the bucket with the index k.
+ * Note: a bucket can be empty!
+ */
 function getChunk(values, totalChunks, chunkIndex) {
   // split all items into N chunks and take just a single chunk
   if (totalChunks < 0) {
@@ -45,7 +50,7 @@ function getChunk(values, totalChunks, chunkIndex) {
   }
 
   const chunks = chunkify(values, totalChunks, true)
-  return chunks[chunkIndex]
+  return chunks[chunkIndex] || []
 }
 
 module.exports = { getChunk, chunkify }

src/empty-spec.cy.js

@@ -0,0 +1,4 @@
+// this file is empty on purpose
+// if there are not specs to run on the current machine
+// then we set the specPattern to this file
+// so Cypress does not exit with an error "no specs found"

src/index.js

@@ -5,6 +5,7 @@ const { getSpecs } = require('find-cypress-specs')
 const ghCore = require('@actions/core')
 const cTable = require('console.table')
 const { getChunk } = require('./chunk')
+const path = require('path')
 
 const label = 'cypress-split:'
 
@@ -119,9 +120,15 @@ function cypressSplit(on, config) {
         .write()
     }
 
-    debug('setting the spec pattern to')
-    debug(splitSpecs)
-    config.specPattern = splitSpecs
+    if (splitSpecs.length) {
+      debug('setting the spec pattern to')
+      debug(splitSpecs)
+      config.specPattern = splitSpecs
+    } else {
+      console.log('%s no specs to run, running an empty spec file', label)
+      config.specPattern = path.resolve(__dirname, './empty-spec.cy.js')
+    }
+
     return config
   }
 }