Try stable versions first, and then try non-head versions

* Fixes #115

Author: eregon

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
       matrix:
         os: [ ubuntu-16.04, ubuntu-18.04, ubuntu-20.04, macos-10.15, macos-11.0, windows-2016, windows-2019 ]
         # Use various version syntax here for testing
-        ruby: [ 2.1, 2.2, 2.3, 2.4, 2.5, 2.6.6, 2.7, ruby-3.0.0-preview1, ruby-head, debug, jruby-9.1, jruby, jruby-head, truffleruby, truffleruby-head ]
+        ruby: [ 2.1, 2.2, 2.3, 2.4, 2.5, 2.6.6, 2.7, 3.0, ruby-head, debug, jruby-9.1, jruby, jruby-head, truffleruby, truffleruby-head ]
         include:
         - { os: windows-2016, ruby: mingw }
         - { os: windows-2019, ruby: mingw }

dist/index.js

@@ -132,7 +132,13 @@ function validateRubyEngineAndVersion(platform, engineVersions, engine, parsedVe
   let version = parsedVersion
   if (!engineVersions.includes(parsedVersion)) {
     const latestToFirstVersion = engineVersions.slice().reverse()
-    const found = latestToFirstVersion.find(v => common.isStableVersion(v) && v.startsWith(parsedVersion))
+    // Try to match stable versions first, so an empty version (engine-only) matches the latest stable version
+    let found = latestToFirstVersion.find(v => common.isStableVersion(v) && v.startsWith(parsedVersion))
+    if (!found) {
+      // Exclude head versions, they must be exact matches
+      found = latestToFirstVersion.find(v => !common.isHeadVersion(v) && v.startsWith(parsedVersion))
+    }
+
     if (found) {
       version = found
     } else {