If uname returns x86_64 on Mac, use x64 binary #214

Even if we were launched by aarch64 Java, see #204 for discussion.

Author: deepy

src/main/kotlin/com/github/gradle/node/util/PlatformHelper.kt

@@ -24,6 +24,7 @@ open class PlatformHelper {
              */
             arch == "arm" || arch.startsWith("aarch") -> property("uname")
                 .mapIf({ it == "armv8l" || it == "aarch64" }) { "arm64" }
+                .mapIf({ it == "x86_64" }) {"x64"}
             arch == "ppc64le" -> "ppc64le"
             arch == "s390x" -> "s390x"
             arch.contains("64") -> "x64"

src/test/groovy/com/github/gradle/node/util/PlatformHelperTest.groovy

@@ -58,6 +58,25 @@ class PlatformHelperTest extends Specification {
         'ppc64le' | 'ppc64le' | 'ppc64le'
     }
 
+    @Unroll
+    def "verify ARM handling Mac OS #archProp (#unameProp)"() {
+        given:
+        this.props.setProperty("os.name", "Mac OS X")
+        this.props.setProperty("os.arch", archProp)
+        this.props.setProperty("uname", unameProp)
+
+        expect:
+        this.helper.getOsName() == "darwin"
+        this.helper.getOsArch() == osArch
+
+        where:
+        archProp  | unameProp | osArch
+        'aarch32' | 'arm'     | 'arm'
+        'aarch64' | 'arm64'   | 'arm64'
+        'aarch64' | 'aarch64' | 'arm64'
+        'aarch64' | 'x86_64'  | 'x64' // This shouldn't really happen but according to PR #204 it does
+    }
+
     def "throw exception if unsupported os"() {
         given:
         this.props.setProperty("os.name", 'Nonsense')