update tool-cache for proxy and fix tests (#57)

update tool-cache for proxy and fix tests

src/main.ts

@@ -0,0 +1,27 @@
+import * as core from '@actions/core';
+import * as cache from './cache';
+
+export async function run() {
+  try {
+    let versionSpec = core.getInput('ruby-version', {required: true});
+    if (!versionSpec) {
+      // deprecated
+      versionSpec = core.getInput('version');
+    }
+
+    // check in the VMs cache first
+    let toolPath: string = await cache.find(versionSpec);
+
+    // TODO: download JIT and/or ruby-build
+
+    if (!toolPath) {
+      core.setFailed(`Version ${versionSpec} not found`);
+      return;
+    }
+
+    core.addPath(toolPath);
+  } catch (error) {
+    // unhandled
+    core.setFailed(error.message);
+  }
+}