diff --git a/subprocess_unittest.cc b/subprocess_unittest.cc
new file mode 100644
index 0000000..430f39b
--- /dev/null
+++ b/subprocess_unittest.cc
@@ -0,0 +1,115 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string>
+#include <vector>
+#include "base/string_util.h"
+#include <glib.h>
+#include <gtest/gtest.h>
+#include "update_engine/subprocess.h"
+#include "update_engine/test_utils.h"
+#include "update_engine/utils.h"
+
+using std::string;
+using std::vector;
+
+namespace chromeos_update_engine {
+
+class SubprocessTest : public ::testing::Test {
+ protected:
+  bool callback_done;
+};
+
+namespace {
+const int kLocalHttpPort = 8080;
+
+void Callback(int return_code, void *p) {
+  EXPECT_EQ(256, return_code);
+  GMainLoop* loop = reinterpret_cast<GMainLoop*>(p);
+  g_main_loop_quit(loop);
+}
+
+gboolean LaunchFalseInMainLoop(gpointer data) {
+  vector<string> cmd;
+  cmd.push_back("/bin/false");
+  Subprocess::Get().Exec(cmd, Callback, data);
+  return FALSE;
+}
+}  // namespace {}
+
+TEST(SubprocessTest, SimpleTest) {
+  GMainLoop *loop = g_main_loop_new(g_main_context_default(), FALSE);
+  g_timeout_add(0, &LaunchFalseInMainLoop, loop);
+  g_main_loop_run(loop);
+  g_main_loop_unref(loop);
+}
+
+namespace {
+void CallbackBad(int return_code, void *p) {
+  CHECK(false) << "should never be called.";
+}
+
+struct CancelTestData {
+  bool spawned;
+  GMainLoop *loop;
+};
+
+gboolean StartAndCancelInRunLoop(gpointer data) {
+  CancelTestData* cancel_test_data = reinterpret_cast<CancelTestData*>(data);
+  vector<string> cmd;
+  cmd.push_back("./test_http_server");
+  uint32 tag = Subprocess::Get().Exec(cmd, CallbackBad, NULL);
+  EXPECT_NE(0, tag);
+  cancel_test_data->spawned = true;
+  printf("spawned\n");
+  // Wait for server to be up and running
+  for (;;) {
+    int status =
+        System(StringPrintf("wget -O /dev/null http://127.0.0.1:%d/foo",
+                            kLocalHttpPort));
+    EXPECT_NE(-1, status) << "system() failed";
+    EXPECT_TRUE(WIFEXITED(status))
+        << "command failed to run or died abnormally";
+    if (0 == WEXITSTATUS(status))
+      break;
+    usleep(100 * 1000);  // 100 ms
+  }
+  Subprocess::Get().CancelExec(tag);
+  return FALSE;
+}
+}  // namespace {}
+
+gboolean ExitWhenDone(gpointer data) {
+  CancelTestData* cancel_test_data = reinterpret_cast<CancelTestData*>(data);
+  if (cancel_test_data->spawned && !Subprocess::Get().SubprocessInFlight()) {
+    // tear down the sub process
+    printf("tear down time\n");
+    int status =
+        System(StringPrintf("wget http://127.0.0.1:%d/quitquitquit",
+                            kLocalHttpPort));
+    EXPECT_NE(-1, status) << "system() failed";
+    EXPECT_TRUE(WIFEXITED(status))
+        << "command failed to run or died abnormally";
+    g_main_loop_quit(cancel_test_data->loop);
+    return FALSE;
+  }
+  return TRUE;
+}
+
+TEST(SubprocessTest, CancelTest) {
+  GMainLoop *loop = g_main_loop_new(g_main_context_default(), FALSE);
+  CancelTestData cancel_test_data;
+  cancel_test_data.spawned = false;
+  cancel_test_data.loop = loop;
+  g_timeout_add(100, &StartAndCancelInRunLoop, &cancel_test_data);
+  g_timeout_add(10, &ExitWhenDone, &cancel_test_data);
+  g_main_loop_run(loop);
+  g_main_loop_unref(loop);
+  printf("here\n");
+}
+
+}  // namespace chromeos_update_engine