Add initial power save blocker spec

spec/api-power-save-blocker-spec.js

@@ -0,0 +1,13 @@
+const {powerSaveBlocker} = require('electron').remote
+const assert = require('assert')
+
+describe('powerSaveBlocker module', () => {
+  it('can be started and stopped', () => {
+    assert.equal(powerSaveBlocker.isStarted(-1), false)
+    const id = powerSaveBlocker.start('prevent-app-suspension')
+    assert.ok(id != null)
+    assert.equal(powerSaveBlocker.isStarted(id), true)
+    powerSaveBlocker.stop(id)
+    assert.equal(powerSaveBlocker.isStarted(id), false)
+  })
+})