3 files changed, 127 insertions, 0 deletions
diff --git a/package.json b/package.json
index ac2ee96..eb53112 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,9 @@
     "type": "git",
     "url": "git://github.com/prettier/vim-prettier.git"
   },
+  "scripts":  {
+    "test": "LOG_LEVEL=error jest"
+  },
   "dependencies": {
     "@prettier/plugin-lua": "0.0.1",
     "@prettier/plugin-php": "^0.10.2",
@@ -15,5 +18,10 @@
     "@prettier/plugin-ruby": "^0.8.0",
     "@prettier/plugin-swift": "prettier/plugin-swift",
     "prettier": "^1.16.4"
+  },
+  "devDependencies": {
+    "colors": "^1.3.2",
+    "jest": "^23.6.0",
+    "vim-driver": "^1.0.0"
   }
 }
diff --git a/tests/fixtures/foo.js b/tests/fixtures/foo.js
new file mode 100644
index 0000000..82955ab
--- /dev/null
+++ b/tests/fixtures/foo.js
@@ -0,0 +1 @@
+const a = () => { return 2; };
diff --git a/tests/formatting.test.js b/tests/formatting.test.js
new file mode 100644
index 0000000..d627921
--- /dev/null
+++ b/tests/formatting.test.js
@@ -0,0 +1,118 @@
+const fs = require('fs');
+const path = require('path');
+const HeadlessRemoteClient = require('vim-driver/dist/HeadlessRemoteClient');
+const Server = require('vim-driver/dist/Server');
+
+const HOST = '127.0.0.1';
+const PORT = 1337;
+const FIXTURES_DIR = `${__dirname}/fixtures`;
+
+let server;
+let remote;
+
+const getBufferContents = async remote =>
+  (await remote.call('getline', [1, '$'])).join('\n');
+
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+const waitUntil = (condition, timeout = 4000) => {
+  return new Promise(resolve => {
+    let isTimedOut = false;
+    let timeoutId = null;
+
+    const check = () => {
+      const promise = condition();
+      promise.then(result => {
+        if (!isTimedOut && result === true) {
+          clearTimeout(timeoutId);
+          resolve();
+        } else if (!isTimedOut) {
+          check();
+        }
+      });
+    };
+
+    timeoutId = setTimeout(() => {
+      isTimedOut = true;
+      resolve();
+    }, timeout);
+  });
+};
+
+const assertFormatting = (file) => {
+  const filename = path.basename(file);
+  test(`Prettier formats ${filename} file with :Prettier command`, async () => {
+    await remote.edit(`${FIXTURES_DIR}/${file}`);
+
+    const lines = await getBufferContents(remote);
+
+    // run sync formatting
+    await remote.execute('Prettier');
+
+    const updatedLines = await getBufferContents(remote);
+
+    // we now check that we have indeed formatted the code
+    expect(updatedLines).not.toBe(lines);
+  });
+
+  test(`Prettier formats ${filename} file with :PrettierAsync command`, async () => {
+    await remote.edit(`${FIXTURES_DIR}/${file}`);
+
+    const lines = await getBufferContents(remote);
+
+    // run async formatting
+    await remote.execute('PrettierAsync');
+
+    const unmodifiedLines = await getBufferContents(remote);
+
+    // async should not happen immediatly so content should still remain the same
+    expect(unmodifiedLines).toBe(lines);
+
+    // we now will wait until prettier has finally updated the content async
+    await waitUntil(async () => (await getBufferContents(remote)) !== lines);
+
+    const updatedLines = await getBufferContents(remote);
+
+    // we now check that we have indeed formatted the code
+    expect(lines).not.toBe(updatedLines);
+  });
+};
+
+beforeAll(async () => {
+  server = new Server();
+  await server.listen(HOST, PORT);
+});
+
+afterAll(async () => {
+  await server.close();
+});
+
+// should ensure that we cache original fixture contents and
+// restore it on the afterEach
+beforeEach(async () => {
+  remote = new HeadlessRemoteClient({host: HOST, port: PORT});
+  await remote.connect(server);
+});
+
+afterEach(async () => {
+  if (remote.isConnected()) {
+    try {
+      const filename = await remote.call('expand', ['%:p']);
+
+      if (filename) {
+        // restore the file
+        await remote.execute('earlier 1d | noautocmd | write');
+      }
+    } catch (e) {
+    } finally {
+      await remote.close();
+    }
+  }
+});
+
+//test('PrettierVersion returns pluggin version', async () => {
+//  const result = await remote.execute('PrettierVersion');
+//  expect(result).toMatchSnapshot();
+//});
+
+// run formatting tests in all fixtures
+fs.readdirSync(FIXTURES_DIR).forEach(file => assertFormatting(file));