unittest: Skip test is traineddata is missing in applybox_test

Many tests have preconditions like a correct version of the test submodule
or installed traineddata files at the right location. They fail or even
crash if those preconditions are not met.

The latest version of Googletest supports skipping single tests with
GTEST_SKIP which is used here to skip tests in applybox_test when
tessdata/eng.traineddata is missing.

Signed-off-by: Stefan Weil <sw@weilnetz.de>

unittest/applybox_test.cc

@@ -39,14 +39,18 @@ class ApplyBoxTest : public testing::Test {
   ApplyBoxTest() { src_pix_ = nullptr; }
   ~ApplyBoxTest() { pixDestroy(&src_pix_); }
 
-  void SetImage(const char* filename) {
+  bool SetImage(const char* filename) {
+    bool found = false;
     pixDestroy(&src_pix_);
     src_pix_ = pixRead(TestDataNameToPath(filename).c_str());
-    api_.Init(TessdataPath().c_str(), "eng", tesseract::OEM_TESSERACT_ONLY);
-    api_.SetPageSegMode(tesseract::PSM_SINGLE_BLOCK);
-    api_.SetImage(src_pix_);
-    api_.SetVariable("tessedit_make_boxes_from_boxes", "1");
-    api_.SetInputName(TestDataNameToPath(filename).c_str());
+    if (api_.Init(TessdataPath().c_str(), "eng", tesseract::OEM_TESSERACT_ONLY) != -1) {
+      api_.SetPageSegMode(tesseract::PSM_SINGLE_BLOCK);
+      api_.SetImage(src_pix_);
+      api_.SetVariable("tessedit_make_boxes_from_boxes", "1");
+      api_.SetInputName(TestDataNameToPath(filename).c_str());
+      found = true;
+    }
+    return found;
   }
 
   // Runs ApplyBoxes (via setting the appropriate variables and Recognize)
@@ -56,7 +60,11 @@ class ApplyBoxTest : public testing::Test {
   // otherwise the input box file is assumed to have character-level boxes.
   void VerifyBoxesAndText(const char* imagefile, const char* truth_str,
                           const char* target_box_file, bool line_mode) {
-    SetImage(imagefile);
+    if (!SetImage(imagefile)) {
+      // eng.traineddata not found or other problem during Init.
+      GTEST_SKIP();
+      return;
+    }
     if (line_mode)
       api_.SetVariable("tessedit_resegment_from_line_boxes", "1");
     else