[DictGen] Add dictgen unit tests directory and add test for ROOT-8566

core/dictgen/CMakeLists.txt

@@ -51,3 +51,5 @@ generateHeader(Dictgen
   ${CMAKE_SOURCE_DIR}/core/dictgen/src/rootcling-argparse.py
   ${CMAKE_BINARY_DIR}/include/rootclingCommandLineOptionsHelp.h
 )
+
+ROOT_ADD_TEST_SUBDIRECTORY(test)

core/dictgen/test/CMakeLists.txt

+# @author Danilo Piparo CERN
+
+ROOT_ADD_GTEST(dictgen_base dictgen_base.cxx LIBRARIES Core)
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core/dictgen/test/dictgen_base.cxx

+#include <TSystem.h>
+#include <TInterpreter.h>
+
+#include "gtest/gtest.h"
+
+#include <fstream>
+
+TEST(DictGen, ExtraIncludes)
+{
+   auto macroName = "myextramacro.C";
+   auto macroCode = R"MACROCODE(
+#ifdef __ROOTCLING__
+#pragma extra_include "myextra.h";
+#endif
+
+#include <iostream>
+
+void a(){}
+)MACROCODE";
+
+    std::ofstream macroFile (macroName);
+    macroFile << macroCode;
+    macroFile.close();
+
+   auto includeName = "myextra.h";
+   auto extraInclude = R"EXTRAINCLUDE(
+#ifndef __EXTRA_HEADER_H
+#define __EXTRA_HEADER_H
+int f(){return 42;};
+#endif
+)EXTRAINCLUDE";
+
+    std::ofstream eiFile (includeName);
+    eiFile << extraInclude;
+    eiFile.close();
+
+
+   // Here we perform these steps:
+   // Compile macro which has a linkdef section with extra includes
+   // The extra includes get parsed. They contain a function, f
+   // The value returned by f is checked to be correct 
+   gInterpreter->ProcessLine(".L myextramacro.C+");
+   auto r = gInterpreter->ProcessLine("f()");
+   EXPECT_EQ(r, 42U);
+
+   gSystem->Unlink(macroName);
+   gSystem->Unlink(includeName);
+}
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