feat: add index starting with 1 support (#124)

* feat: add index 1 support

* add CI job

* debug message

.github/workflows/ci.yml

@@ -142,6 +142,24 @@ jobs:
       component: true
       n: 2
 
+  # using SPLIT_INDEX1 to start index at 1
+  test-index1:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Checkout 🛎
+        uses: actions/checkout@v4
+
+      - name: Run split Cypress E2E tests 🧪
+        # https://github.com/cypress-io/github-action
+        uses: cypress-io/github-action@v5
+        # using operating system process environment variables
+        env:
+          SPEC: 'cypress/e2e/spec-b.cy.js,cypress/e2e/spec-e.cy.js'
+          SPLIT: 2
+          # should run the first spec "spec-b" in the list
+          SPLIT_INDEX1: 1
+          DEBUG: 'cypress-split'
+
   release:
     if: github.ref == 'refs/heads/main'
     needs:
@@ -154,6 +172,7 @@ jobs:
         test-no-summary,
         test-user-spec-list,
         test-subfolder,
+        test-index1,
       ]
     runs-on: ubuntu-22.04
     steps:

README.md

@@ -221,6 +221,14 @@ job2: npx cypress run --env split=3,splitIndex=1
 job3: npx cypress run --env split=3,splitIndex=2
 ```
 
+### Index starts at 1
+
+Some CIs provide an agent index that already starts at 1. You can pass it via `SPLIT_INDEX1` instead of `SPLIT_INDEX`
+
+```
+job1: SPLIT=3 SPLIT_INDEX1=1 npx cypress run
+```
+
 ## CI summary
 
 To skip GitHub Actions summary, set an environment variable `SPLIT_SUMMARY=false`. By default, this plugin generates the summary.

src/index.js

@@ -68,6 +68,20 @@ function cypressSplit(on, config) {
 
   let SPLIT = process.env.SPLIT || config.env.split || config.env.SPLIT
   let SPLIT_INDEX = process.env.SPLIT_INDEX || config.env.splitIndex
+
+  // some CI systems like TeamCity provide agent index starting with 1
+  // let's check for SPLIT_INDEX1 and if it is set,
+  // use it instead of zero-based SPLIT_INDEX
+  if (process.env.SPLIT_INDEX1 || config.env.splitIndex) {
+    const indexOne = process.env.SPLIT_INDEX1 || config.env.splitIndex
+    SPLIT_INDEX = Number(indexOne) - 1
+    debug(
+      'set SPLIT_INDEX to %d from index starting with 1 "%s"',
+      SPLIT_INDEX,
+      indexOne,
+    )
+  }
+
   // potentially a list of files to run / split
   let SPEC = process.env.SPEC || config.env.spec || config.env.SPEC
   let specs