diff --git a/tests/unit/resources_test.cpp b/tests/unit/resources_test.cpp
index c3f7271..3027443 100644
--- a/tests/unit/resources_test.cpp
+++ b/tests/unit/resources_test.cpp
@@ -14,12 +14,62 @@
  * limitations under the License.
  */
 
-#include <string>
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
 
+#include <memory>
+#include <string>
+#include <vector>
+
+#include <android-base/file.h>
+#include <android-base/strings.h>
 #include <gtest/gtest.h>
+#include <png.h>
 
 #include "common/test_constants.h"
 #include "minui/minui.h"
+#include "private/resources.h"
+
+static const std::string kLocale = "zu";
+
+static const std::vector<std::string> kResourceImagesDirs{
+  "res-mdpi/images/",   "res-hdpi/images/",    "res-xhdpi/images/",
+  "res-xxhdpi/images/", "res-xxxhdpi/images/",
+};
+
+static int png_filter(const dirent* de) {
+  if (de->d_type != DT_REG || !android::base::EndsWith(de->d_name, "_text.png")) {
+    return 0;
+  }
+  return 1;
+}
+
+// Finds out all the PNG files to test, which stay under the same dir with the executabl..
+static std::vector<std::string> add_files() {
+  std::vector<std::string> files;
+  for (const std::string& images_dir : kResourceImagesDirs) {
+    static std::string exec_dir = android::base::GetExecutableDirectory();
+    std::string dir_path = exec_dir + "/" + images_dir;
+    dirent** namelist;
+    int n = scandir(dir_path.c_str(), &namelist, png_filter, alphasort);
+    if (n == -1) {
+      printf("Failed to scandir %s: %s\n", dir_path.c_str(), strerror(errno));
+      continue;
+    }
+    if (n == 0) {
+      printf("No file is added for test in %s\n", dir_path.c_str());
+    }
+
+    while (n--) {
+      std::string file_path = dir_path + namelist[n]->d_name;
+      files.push_back(file_path);
+      free(namelist[n]);
+    }
+    free(namelist);
+  }
+  return files;
+}
 
 TEST(ResourcesTest, res_create_multi_display_surface) {
   GRSurface** frames;
@@ -35,3 +85,52 @@
   }
   free(frames);
 }
+
+class ResourcesTest : public testing::TestWithParam<std::string> {
+ public:
+  static std::vector<std::string> png_list;
+
+ protected:
+  void SetUp() override {
+    png_ = std::make_unique<PngHandler>(GetParam());
+    ASSERT_TRUE(png_);
+
+    ASSERT_EQ(PNG_COLOR_TYPE_GRAY, png_->color_type()) << "Recovery expects grayscale PNG file.";
+    ASSERT_LT(static_cast<png_uint_32>(5), png_->width());
+    ASSERT_LT(static_cast<png_uint_32>(0), png_->height());
+    ASSERT_EQ(1, png_->channels()) << "Recovery background text images expects 1-channel PNG file.";
+  }
+
+  std::unique_ptr<PngHandler> png_{ nullptr };
+};
+
+// Parses a png file and tests if it's qualified for the background text image under recovery.
+TEST_P(ResourcesTest, ValidateLocale) {
+  std::vector<unsigned char> row(png_->width());
+  for (png_uint_32 y = 0; y < png_->height(); ++y) {
+    png_read_row(png_->png_ptr(), row.data(), nullptr);
+    int w = (row[1] << 8) | row[0];
+    int h = (row[3] << 8) | row[2];
+    int len = row[4];
+    EXPECT_LT(0, w);
+    EXPECT_LT(0, h);
+    EXPECT_LT(0, len) << "Locale string should be non-empty.";
+    EXPECT_NE(0, row[5]) << "Locale string is missing.";
+
+    ASSERT_GE(png_->height(), y + 1 + h) << "Locale: " << kLocale << " is not found in the file.";
+    char* loc = reinterpret_cast<char*>(&row[5]);
+    if (matches_locale(loc, kLocale.c_str())) {
+      EXPECT_TRUE(android::base::StartsWith(loc, kLocale));
+      break;
+    }
+    for (int i = 0; i < h; ++i, ++y) {
+      png_read_row(png_->png_ptr(), row.data(), nullptr);
+    }
+  }
+}
+
+std::vector<std::string> ResourcesTest::png_list = add_files();
+
+INSTANTIATE_TEST_CASE_P(BackgroundTextValidation, ResourcesTest,
+                        ::testing::ValuesIn(ResourcesTest::png_list.cbegin(),
+                                            ResourcesTest::png_list.cend()));