Add unit tests for Photoshop::isIrb().

It has been detected that we need to always pass the size==4 in the call
to isIrb. Probably it is better to remove that parameter and document
that it is assumed for the buffer to have a length of 4 bytes.

Author: piponazo

unitTests/CMakeLists.txt

@@ -18,6 +18,7 @@ add_executable(unit_tests
     test_jp2image_int.cpp
     test_IptcKey.cpp
     test_LangAltValueRead.cpp
+    test_Photoshop.cpp
     test_pngimage.cpp
     test_safe_op.cpp
     test_slice.cpp

unitTests/test_Photoshop.cpp

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <exiv2/jpgimage.hpp>
+
+#include <gtest/gtest.h>
+
+using namespace Exiv2;
+
+namespace {
+constexpr std::array validMarkers{"8BIM", "AgHg", "DCSR", "PHUT"};
+}
+
+TEST(Photoshop_isIrb, returnsTrueWithValidMarkers) {
+  for (const auto& marker : validMarkers) {
+    ASSERT_TRUE(Photoshop::isIrb(reinterpret_cast<const byte*>(marker), 4));
+  }
+}
+
+
+TEST(Photoshop_isIrb, returnsFalseWithInvalidMarkers) {
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("7BIM"), 4));
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("AGHg"), 4));
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("dcsr"), 4));
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("LUIS"), 4));
+}
+
+TEST(Photoshop_isIrb, returnsFalseWithInvalidSize) {
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("8BIM"), 3));
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("8BIM"), 0));
+  ASSERT_FALSE(Photoshop::isIrb(reinterpret_cast<const byte *>("8BIM"), 5));
+}