diff --git a/.gitignore b/.gitignore
index fdd41e0..163f79a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 package-lock.json
 .idea/
 node_modules/
+coverage/
diff --git a/package.json b/package.json
index 89439b7..3597ddf 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,8 @@
   "version": "1.3.1-r1",
   "description": "A Node.js module for interfacing with Repertory's remote mount API",
   "scripts": {
-    "test": "jest"
+    "test": "jest",
+    "coverage": "jest --collect-coverage"
   },
   "keywords": [
     "repertory",
diff --git a/src/__tests__/connection_pool.test.js b/src/__tests__/connection_pool.test.js
new file mode 100644
index 0000000..01b1dbd
--- /dev/null
+++ b/src/__tests__/connection_pool.test.js
@@ -0,0 +1,43 @@
+import connection_pool from '../networking/connection_pool';
+import packet from '../networking/packet';
+import connection from '../networking/connection';
+
+jest.mock('../networking/connection');
+
+test(`construction fails if pool size is <= 1`, () => {
+  expect(() => new connection_pool(1)).toThrow(Error);
+  expect(() => new connection_pool(0)).toThrow(Error);
+  expect(() => new connection_pool(-1)).toThrow(Error);
+});
+
+test(`error on socket release is ignored`, async () => {
+
+  const conn = new connection_pool(2, '', 20000);
+  let invoked = false;
+  jest.spyOn(conn.pool, 'acquire').mockImplementation(() => {
+    return {
+      release: () => {
+        invoked = true;
+        throw new Error('mock release error');
+      },
+    }
+  });
+
+  const mock_send = jest.fn();
+  connection.prototype.send = async () => {
+    return mock_send();
+  };
+  mock_send.mockResolvedValue(0);
+
+  expect(await conn.send('', new packet())).toEqual(0);
+  expect(invoked).toBeTruthy();
+});
+
+test(`send fails if acquire fails`, async () => {
+  const conn = new connection_pool(2, '', 20000);
+  jest.spyOn(conn.pool, 'acquire').mockImplementation(() => {
+    throw new Error('mock acquire exception');
+  });
+
+  await expect(conn.send('', new packet())).rejects.toThrow(Error);
+});
diff --git a/src/__tests__/file.test.js b/src/__tests__/file.test.js
new file mode 100644
index 0000000..6e1ab4f
--- /dev/null
+++ b/src/__tests__/file.test.js
@@ -0,0 +1,49 @@
+import file from '../io/file';
+
+jest.mock('../ops/index.js', () => (
+  {
+    ...(jest.requireActual('../ops/index.js')),
+    close_file: jest.fn(),
+  }
+));
+
+import {close_file} from '../ops/index';
+
+test(`can close a closed file`, async () => {
+  const f = new file();
+  expect(await f.close()).toEqual(0);
+});
+
+test(`'get_size' fails on closed file`, async () => {
+  const f = new file();
+  await expect(f.get_size()).rejects.toThrow(Error);
+});
+
+test(`'read' fails on closed file`, async () => {
+  const f = new file();
+  await expect(f.read(0, 10)).rejects.toThrow(Error);
+});
+
+test(`'truncate' fails on closed file`, async () => {
+  const f = new file();
+  await expect(f.truncate(0)).rejects.toThrow(Error);
+});
+
+test(`'write' fails on closed file`, async () => {
+  const f = new file();
+  await expect(f.write(0, Buffer.alloc(2))).rejects.toThrow(Error);
+});
+
+test(`handle is set to null on close`, async () => {
+  const f = new file(null, 1, '/path');
+  close_file.mockReturnValue(0);
+  expect(await f.close()).toEqual(0);
+  expect(f.handle).toBeNull();
+});
+
+test(`handle is not changed on close if return is not 0`, async () => {
+  const f = new file(null, 1, '/path');
+  close_file.mockReturnValue(1);
+  expect(await f.close()).toEqual(1);
+  expect(f.handle).toBe(1);
+});
diff --git a/src/io/file.js b/src/io/file.js
index 11773a2..091cbbc 100644
--- a/src/io/file.js
+++ b/src/io/file.js
@@ -5,7 +5,7 @@ let next_thread_id = 1;
 export default class file {
   constructor(conn, handle, remote_path) {
     this.conn = conn;
-    this.handle = handle;
+    this.handle = handle || null;
     this.remote_path = remote_path;
     this.thread_id = next_thread_id++;
   }