Use the correct repository URL for scoped packages when checking for package existence

cli/api.js

@@ -69,14 +69,25 @@ function save() {
 }
 
 function existsOnNpm(plugin) {
-  const name = plugin.split('#')[0].split('@')[0];
+  const name = getPackageName(plugin);
   return got.get(registryUrl + name.toLowerCase(), {timeout: 10000, json: true}).then(res => {
     if (!res.body.versions) {
       return Promise.reject(res);
     }
   });
 }
 
+function getPackageName(plugin) {
+  const isScoped = plugin[0] === '@';
+  const nameWithoutVersion = plugin.split('#')[0];
+
+  if (isScoped) {
+    return '@' + nameWithoutVersion.split('@')[1].replace('/', '%2f');
+  }
+
+  return nameWithoutVersion.split('@')[0];
+}
+
 function install(plugin, locally) {
   const array = locally ? getLocalPlugins() : getPlugins();
   return new Promise((resolve, reject) => {

test/unit/cli-api.test.js

@@ -0,0 +1,44 @@
+import test from 'ava';
+const proxyquire = require('proxyquire').noCallThru();
+
+test('existsOnNpm() builds the url for non-scoped packages', t => {
+  let getUrl;
+  const {existsOnNpm} = proxyquire('../../cli/api', {
+    got: {
+      get(url) {
+        getUrl = url;
+        return Promise.resolve({
+          body: {
+            versions: []
+          }
+        });
+      }
+    },
+    'registry-url': () => 'https://registry.npmjs.org/'
+  });
+
+  return existsOnNpm('pkg').then(() => {
+    t.is(getUrl, 'https://registry.npmjs.org/pkg');
+  });
+});
+
+test('existsOnNpm() builds the url for scoped packages', t => {
+  let getUrl;
+  const {existsOnNpm} = proxyquire('../../cli/api', {
+    got: {
+      get(url) {
+        getUrl = url;
+        return Promise.resolve({
+          body: {
+            versions: []
+          }
+        });
+      }
+    },
+    'registry-url': () => 'https://registry.npmjs.org/'
+  });
+
+  return existsOnNpm('@scope/pkg').then(() => {
+    t.is(getUrl, 'https://registry.npmjs.org/@scope%2fpkg');
+  });
+});