Add notes about Windows in the README

* It already ran on the feature branch.

.github/workflows/test.yml

@@ -2,6 +2,7 @@ name: Test this action
 on:
   push:
     branches-ignore:
+    - master
     - v1
     tags-ignore:
     - '*'

README.md

@@ -123,6 +123,17 @@ This uses the [cache action](https://github.com/actions/cache).
 The code above is a more complete version of the [Ruby - Bundler example](https://github.com/actions/cache/blob/master/examples.md#ruby---bundler).
 Make sure to include `use-ruby` in the `key` to avoid conflicting with previous caches.
 
+## Windows
+
+Note that running CI on Windows can be quite challenging if you are not very familiar with Windows.
+It is recommended to first get your build working on Ubuntu and macOS before trying Windows.
+
+* The default shell on Windows is not Bash but [PowerShell](https://help.github.com/en/actions/automating-your-workflow-with-github-actions/workflow-syntax-for-github-actions#using-a-specific-shell).
+  This can lead issues such as multi-line scripts [not working as expected](https://github.com/ruby/setup-ruby/issues/13).
+* The `PATH` contains [multiple compiler toolchains](https://github.com/ruby/setup-ruby/issues/19). Use `where` to debug which tool is used.
+* MSYS2 is prepended to the `PATH`, similar to what RubyInstaller2 does.
+* JRuby on Windows has a known bug that `bundle exec rake` [fails](https://github.com/ruby/setup-ruby/issues/18).
+
 ## Limitations
 
 * This action currently only works with GitHub-hosted runners, not private runners.

dist/index.js

@@ -7896,7 +7896,7 @@ async function install(platform, ruby) {
   const drive = (process.env['GITHUB_WORKSPACE'] || 'C')[0]
 
   const downloadPath = await tc.downloadTool(url)
-  await exec.exec(`7z x ${downloadPath} -xr!${base}\\share\\doc -o${drive}:\\`)
+  await exec.exec('7z', ['x', downloadPath, `-xr!${base}\\share\\doc`, `-o${drive}:\\`], { silent: true })
   const rubyPrefix = `${drive}:\\${base}`
 
   const [hostedRuby, msys2] = await linkMSYS2()
@@ -7929,10 +7929,8 @@ async function linkMSYS2() {
 }
 
 function setupPath(msys2, rubyPrefix) {
-  let path = process.env['PATH'].split(';')
-
-  // Remove conflicting dev tools from PATH
-  path = path.filter(e => !e.match(/\b(Chocolatey|CMake|mingw64|OpenSSL|Strawberry)\b/))
+  const originalPath = process.env['PATH'].split(';')
+  let path = originalPath.slice()
 
   // Remove default Ruby in PATH
   path = path.filter(e => !e.match(/\bRuby\b/))
@@ -7945,6 +7943,13 @@ function setupPath(msys2, rubyPrefix) {
   // Add the downloaded Ruby in PATH
   path.unshift(`${rubyPrefix}\\bin`)
 
+  console.log("Entries removed from PATH to avoid conflicts with Ruby:")
+  for (const entry of originalPath) {
+    if (!path.includes(entry)) {
+      console.log(entry)
+    }
+  }
+
   const newPath = path.join(';')
   core.exportVariable('PATH', newPath)
 }

windows.js

@@ -29,7 +29,7 @@ export async function install(platform, ruby) {
   const drive = (process.env['GITHUB_WORKSPACE'] || 'C')[0]
 
   const downloadPath = await tc.downloadTool(url)
-  await exec.exec(`7z x ${downloadPath} -xr!${base}\\share\\doc -o${drive}:\\`)
+  await exec.exec('7z', ['x', downloadPath, `-xr!${base}\\share\\doc`, `-o${drive}:\\`], { silent: true })
   const rubyPrefix = `${drive}:\\${base}`
 
   const [hostedRuby, msys2] = await linkMSYS2()
@@ -62,10 +62,8 @@ async function linkMSYS2() {
 }
 
 export function setupPath(msys2, rubyPrefix) {
-  let path = process.env['PATH'].split(';')
-
-  // Remove conflicting dev tools from PATH
-  path = path.filter(e => !e.match(/\b(Chocolatey|CMake|mingw64|OpenSSL|Strawberry)\b/))
+  const originalPath = process.env['PATH'].split(';')
+  let path = originalPath.slice()
 
   // Remove default Ruby in PATH
   path = path.filter(e => !e.match(/\bRuby\b/))
@@ -78,6 +76,13 @@ export function setupPath(msys2, rubyPrefix) {
   // Add the downloaded Ruby in PATH
   path.unshift(`${rubyPrefix}\\bin`)
 
+  console.log("Entries removed from PATH to avoid conflicts with Ruby:")
+  for (const entry of originalPath) {
+    if (!path.includes(entry)) {
+      console.log(entry)
+    }
+  }
+
   const newPath = path.join(';')
   core.exportVariable('PATH', newPath)
 }