diff --git a/tests/Android.mk b/tests/Android.mk
index 3f3c433..9d83c9a 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -29,21 +29,30 @@
 # Component tests
 include $(CLEAR_VARS)
 LOCAL_CLANG := true
+LOCAL_CFLAGS += -Wno-unused-parameter
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_MODULE := recovery_component_test
 LOCAL_C_INCLUDES := bootable/recovery
-LOCAL_SRC_FILES := component/verifier_test.cpp
+LOCAL_SRC_FILES := \
+    component/verifier_test.cpp \
+    component/applypatch_test.cpp
 LOCAL_FORCE_STATIC_EXECUTABLE := true
 LOCAL_STATIC_LIBRARIES := \
+    libapplypatch \
+    libotafault \
+    libmtdutils \
     libbase \
     libverifier \
     libmincrypt \
+    libcrypto_static \
     libminui \
     libminzip \
     libcutils \
+    libbz \
+    libz \
     libc
 
-testdata_out_path := $(TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)
+testdata_out_path := $(TARGET_OUT_DATA_NATIVE_TESTS)/recovery
 testdata_files := $(call find-subdir-files, testdata/*)
 
 GEN := $(addprefix $(testdata_out_path)/, $(testdata_files))
diff --git a/tests/common/test_constants.h b/tests/common/test_constants.h
new file mode 100644
index 0000000..3490f68
--- /dev/null
+++ b/tests/common/test_constants.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agree to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef _OTA_TEST_CONSTANTS_H
+#define _OTA_TEST_CONSTANTS_H
+
+#if defined(__LP64__)
+#define NATIVE_TEST_PATH "/nativetest64"
+#else
+#define NATIVE_TEST_PATH "/nativetest"
+#endif
+
+#endif
diff --git a/tests/component/applypatch_test.cpp b/tests/component/applypatch_test.cpp
new file mode 100644
index 0000000..b44ddd1
--- /dev/null
+++ b/tests/component/applypatch_test.cpp
@@ -0,0 +1,392 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agree to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <fcntl.h>
+#include <gtest/gtest.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/types.h>
+#include <time.h>
+
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/stringprintf.h>
+#include <android-base/test_utils.h>
+
+#include "applypatch/applypatch.h"
+#include "common/test_constants.h"
+#include "openssl/sha.h"
+#include "print_sha1.h"
+
+static const std::string DATA_PATH = getenv("ANDROID_DATA");
+static const std::string TESTDATA_PATH = "/recovery/testdata";
+static const std::string WORK_FS = "/data";
+
+static std::string sha1sum(const std::string& fname) {
+    uint8_t digest[SHA_DIGEST_LENGTH];
+    std::string data;
+    android::base::ReadFileToString(fname, &data);
+
+    SHA1((const uint8_t*)data.c_str(), data.size(), digest);
+    return print_sha1(digest);
+}
+
+static void mangle_file(const std::string& fname) {
+    FILE* fh = fopen(&fname[0], "w");
+    int r;
+    for (int i=0; i < 1024; i++) {
+        r = rand();
+        fwrite(&r, sizeof(short), 1, fh);
+    }
+    fclose(fh);
+}
+
+static bool file_cmp(std::string& f1, std::string& f2) {
+    std::string c1;
+    std::string c2;
+    android::base::ReadFileToString(f1, &c1);
+    android::base::ReadFileToString(f2, &c2);
+    return c1 == c2;
+}
+
+static std::string from_testdata_base(const std::string fname) {
+    return android::base::StringPrintf("%s%s%s/%s",
+            &DATA_PATH[0],
+            &NATIVE_TEST_PATH[0],
+            &TESTDATA_PATH[0],
+            &fname[0]);
+}
+
+class ApplyPatchTest : public ::testing::Test {
+    public:
+        static void SetUpTestCase() {
+            // set up files
+            old_file = from_testdata_base("old.file");
+            new_file = from_testdata_base("new.file");
+            patch_file = from_testdata_base("patch.bsdiff");
+            rand_file = "/cache/applypatch_test_rand.file";
+            cache_file = "/cache/saved.file";
+
+            // write stuff to rand_file
+            android::base::WriteStringToFile("hello", rand_file);
+
+            // set up SHA constants
+            old_sha1 = sha1sum(old_file);
+            new_sha1 = sha1sum(new_file);
+            srand(time(NULL));
+            bad_sha1_a = android::base::StringPrintf("%040x", rand());
+            bad_sha1_b = android::base::StringPrintf("%040x", rand());
+
+            struct stat st;
+            stat(&new_file[0], &st);
+            new_size = st.st_size;
+        }
+
+        static std::string old_file;
+        static std::string new_file;
+        static std::string rand_file;
+        static std::string cache_file;
+        static std::string patch_file;
+
+        static std::string old_sha1;
+        static std::string new_sha1;
+        static std::string bad_sha1_a;
+        static std::string bad_sha1_b;
+
+        static size_t new_size;
+};
+
+std::string ApplyPatchTest::old_file;
+std::string ApplyPatchTest::new_file;
+
+static void cp(std::string src, std::string tgt) {
+    std::string cmd = android::base::StringPrintf("cp %s %s",
+            &src[0],
+            &tgt[0]);
+    system(&cmd[0]);
+}
+
+static void backup_old() {
+    cp(ApplyPatchTest::old_file, ApplyPatchTest::cache_file);
+}
+
+static void restore_old() {
+    cp(ApplyPatchTest::cache_file, ApplyPatchTest::old_file);
+}
+
+class ApplyPatchCacheTest : public ApplyPatchTest {
+    public:
+        virtual void SetUp() {
+            backup_old();
+        }
+
+        virtual void TearDown() {
+            restore_old();
+        }
+};
+
+class ApplyPatchFullTest : public ApplyPatchCacheTest {
+    public:
+        static void SetUpTestCase() {
+            ApplyPatchTest::SetUpTestCase();
+            unsigned long free_kb = FreeSpaceForFile(&WORK_FS[0]);
+            ASSERT_GE(free_kb * 1024, new_size * 3 / 2);
+            output_f = new TemporaryFile();
+            output_loc = std::string(output_f->path);
+
+            struct FileContents fc;
+
+            ASSERT_EQ(0, LoadFileContents(&rand_file[0], &fc));
+            Value* patch1 = new Value();
+            patch1->type = VAL_BLOB;
+            patch1->size = fc.data.size();
+            patch1->data = static_cast<char*>(malloc(fc.data.size()));
+            memcpy(patch1->data, fc.data.data(), fc.data.size());
+            patches.push_back(patch1);
+
+            ASSERT_EQ(0, LoadFileContents(&patch_file[0], &fc));
+            Value* patch2 = new Value();
+            patch2->type = VAL_BLOB;
+            patch2->size = fc.st.st_size;
+            patch2->data = static_cast<char*>(malloc(fc.data.size()));
+            memcpy(patch2->data, fc.data.data(), fc.data.size());
+            patches.push_back(patch2);
+        }
+        static void TearDownTestCase() {
+            delete output_f;
+            for (auto it = patches.begin(); it != patches.end(); ++it) {
+                free((*it)->data);
+                delete *it;
+            }
+            patches.clear();
+        }
+
+        static std::vector<Value*> patches;
+        static TemporaryFile* output_f;
+        static std::string output_loc;
+};
+
+class ApplyPatchDoubleCacheTest : public ApplyPatchFullTest {
+    public:
+        virtual void SetUp() {
+            ApplyPatchCacheTest::SetUp();
+            cp(cache_file, "/cache/reallysaved.file");
+        }
+
+        virtual void TearDown() {
+            cp("/cache/reallysaved.file", cache_file);
+            ApplyPatchCacheTest::TearDown();
+        }
+};
+
+std::string ApplyPatchTest::rand_file;
+std::string ApplyPatchTest::patch_file;
+std::string ApplyPatchTest::cache_file;
+std::string ApplyPatchTest::old_sha1;
+std::string ApplyPatchTest::new_sha1;
+std::string ApplyPatchTest::bad_sha1_a;
+std::string ApplyPatchTest::bad_sha1_b;
+
+size_t ApplyPatchTest::new_size;
+
+std::vector<Value*> ApplyPatchFullTest::patches;
+TemporaryFile* ApplyPatchFullTest::output_f;
+std::string ApplyPatchFullTest::output_loc;
+
+TEST_F(ApplyPatchTest, CheckModeSingle) {
+    char* s = &old_sha1[0];
+    ASSERT_EQ(0, applypatch_check(&old_file[0], 1, &s));
+}
+
+TEST_F(ApplyPatchTest, CheckModeMultiple) {
+    char* argv[3] = {
+        &bad_sha1_a[0],
+        &old_sha1[0],
+        &bad_sha1_b[0]
+    };
+    ASSERT_EQ(0, applypatch_check(&old_file[0], 3, argv));
+}
+
+TEST_F(ApplyPatchTest, CheckModeFailure) {
+    char* argv[2] = {
+        &bad_sha1_a[0],
+        &bad_sha1_b[0]
+    };
+    ASSERT_NE(0, applypatch_check(&old_file[0], 2, argv));
+}
+
+TEST_F(ApplyPatchCacheTest, CheckCacheCorruptedSingle) {
+    mangle_file(old_file);
+    char* s = &old_sha1[0];
+    ASSERT_EQ(0, applypatch_check(&old_file[0], 1, &s));
+}
+
+TEST_F(ApplyPatchCacheTest, CheckCacheCorruptedMultiple) {
+    mangle_file(old_file);
+    char* argv[3] = {
+        &bad_sha1_a[0],
+        &old_sha1[0],
+        &bad_sha1_b[0]
+    };
+    ASSERT_EQ(0, applypatch_check(&old_file[0], 3, argv));
+}
+
+TEST_F(ApplyPatchCacheTest, CheckCacheCorruptedFailure) {
+    mangle_file(old_file);
+    char* argv[2] = {
+        &bad_sha1_a[0],
+        &bad_sha1_b[0]
+    };
+    ASSERT_NE(0, applypatch_check(&old_file[0], 2, argv));
+}
+
+TEST_F(ApplyPatchCacheTest, CheckCacheMissingSingle) {
+    unlink(&old_file[0]);
+    char* s = &old_sha1[0];
+    ASSERT_EQ(0, applypatch_check(&old_file[0], 1, &s));
+}
+
+TEST_F(ApplyPatchCacheTest, CheckCacheMissingMultiple) {
+    unlink(&old_file[0]);
+    char* argv[3] = {
+        &bad_sha1_a[0],
+        &old_sha1[0],
+        &bad_sha1_b[0]
+    };
+    ASSERT_EQ(0, applypatch_check(&old_file[0], 3, argv));
+}
+
+TEST_F(ApplyPatchCacheTest, CheckCacheMissingFailure) {
+    unlink(&old_file[0]);
+    char* argv[2] = {
+        &bad_sha1_a[0],
+        &bad_sha1_b[0]
+    };
+    ASSERT_NE(0, applypatch_check(&old_file[0], 2, argv));
+}
+
+TEST_F(ApplyPatchFullTest, ApplyInPlace) {
+    std::vector<char*> sha1s;
+    sha1s.push_back(&bad_sha1_a[0]);
+    sha1s.push_back(&old_sha1[0]);
+
+    int ap_result = applypatch(&old_file[0],
+            "-",
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_EQ(0, ap_result);
+    ASSERT_TRUE(file_cmp(old_file, new_file));
+    // reapply, applypatch is idempotent so it should succeed
+    ap_result = applypatch(&old_file[0],
+            "-",
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_EQ(0, ap_result);
+    ASSERT_TRUE(file_cmp(old_file, new_file));
+}
+
+TEST_F(ApplyPatchFullTest, ApplyInNewLocation) {
+    std::vector<char*> sha1s;
+    sha1s.push_back(&bad_sha1_a[0]);
+    sha1s.push_back(&old_sha1[0]);
+    int ap_result = applypatch(&old_file[0],
+            &output_loc[0],
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_EQ(0, ap_result);
+    ASSERT_TRUE(file_cmp(output_loc, new_file));
+    ap_result = applypatch(&old_file[0],
+            &output_loc[0],
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_EQ(0, ap_result);
+    ASSERT_TRUE(file_cmp(output_loc, new_file));
+}
+
+TEST_F(ApplyPatchFullTest, ApplyCorruptedInNewLocation) {
+    mangle_file(old_file);
+    std::vector<char*> sha1s;
+    sha1s.push_back(&bad_sha1_a[0]);
+    sha1s.push_back(&old_sha1[0]);
+    int ap_result = applypatch(&old_file[0],
+            &output_loc[0],
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_EQ(0, ap_result);
+    ASSERT_TRUE(file_cmp(output_loc, new_file));
+    ap_result = applypatch(&old_file[0],
+            &output_loc[0],
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_EQ(0, ap_result);
+    ASSERT_TRUE(file_cmp(output_loc, new_file));
+}
+
+TEST_F(ApplyPatchDoubleCacheTest, ApplyDoubleCorruptedInNewLocation) {
+    mangle_file(old_file);
+    mangle_file(cache_file);
+
+    std::vector<char*> sha1s;
+    sha1s.push_back(&bad_sha1_a[0]);
+    sha1s.push_back(&old_sha1[0]);
+    int ap_result = applypatch(&old_file[0],
+            &output_loc[0],
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_NE(0, ap_result);
+    ASSERT_FALSE(file_cmp(output_loc, new_file));
+    ap_result = applypatch(&old_file[0],
+            &output_loc[0],
+            &new_sha1[0],
+            new_size,
+            2,
+            sha1s.data(),
+            patches.data(),
+            nullptr);
+    ASSERT_NE(0, ap_result);
+    ASSERT_FALSE(file_cmp(output_loc, new_file));
+}
diff --git a/tests/component/verifier_test.cpp b/tests/component/verifier_test.cpp
index c54aa11..73f6ac9 100644
--- a/tests/component/verifier_test.cpp
+++ b/tests/component/verifier_test.cpp
@@ -29,18 +29,13 @@
 #include <android-base/stringprintf.h>
 
 #include "common.h"
+#include "common/test_constants.h"
 #include "mincrypt/sha.h"
 #include "mincrypt/sha256.h"
 #include "minzip/SysUtil.h"
 #include "ui.h"
 #include "verifier.h"
 
-#if defined(__LP64__)
-#define NATIVE_TEST_PATH "/nativetest64"
-#else
-#define NATIVE_TEST_PATH "/nativetest"
-#endif
-
 static const char* DATA_PATH = getenv("ANDROID_DATA");
 static const char* TESTDATA_PATH = "/recovery/testdata/";
 
diff --git a/tests/testdata/new.file b/tests/testdata/new.file
new file mode 100644
index 0000000..cdeb8fd
--- /dev/null
+++ b/tests/testdata/new.file
Binary files differ
diff --git a/tests/testdata/old.file b/tests/testdata/old.file
new file mode 100644
index 0000000..166c873
--- /dev/null
+++ b/tests/testdata/old.file
Binary files differ
diff --git a/tests/testdata/patch.bsdiff b/tests/testdata/patch.bsdiff
new file mode 100644
index 0000000..b78d385
--- /dev/null
+++ b/tests/testdata/patch.bsdiff
Binary files differ