only add .mini tests if dune-testtools is present

cmake/modules/DuneXTTesting.cmake

@@ -67,25 +67,29 @@ macro(BEGIN_TESTCASES) # https://cmake.org/cmake/help/v3.0/module/FindGTest.html
                    minifile
                    ${source})
     if(EXISTS ${minifile})
-      dune_add_system_test(SOURCE
-                           ${source}
-                           ${COMMON_HEADER}
-                           INIFILE
-                           ${minifile}
-                           BASENAME
-                           test_${testbase}
-                           CREATED_TARGETS
-                           targetlist_${testbase}
-                           ADDED_TESTS
-                           testlist_${testbase}
-                           SCRIPT
-                           dune_xt_execute.py
-                           ${DEBUG_MACRO_TESTS})
-      foreach(target ${targetlist_${testbase}})
-        target_link_libraries(${target} ${ARGN} ${COMMON_LIBS} ${GRID_LIBS} gtest_dune_xt_common)
-        list(APPEND dxt_test_binaries ${target})
-        set(dxt_test_names_${target} ${testlist_${testbase}_${target}})
-      endforeach(target)
+        if(dune-testtools_FOUND)
+              dune_add_system_test(SOURCE
+                                   ${source}
+                                   ${COMMON_HEADER}
+                                   INIFILE
+                                   ${minifile}
+                                   BASENAME
+                                   test_${testbase}
+                                   CREATED_TARGETS
+                                   targetlist_${testbase}
+                                   ADDED_TESTS
+                                   testlist_${testbase}
+                                   SCRIPT
+                                   dune_xt_execute.py
+                                   ${DEBUG_MACRO_TESTS})
+              foreach(target ${targetlist_${testbase}})
+                target_link_libraries(${target} ${ARGN} ${COMMON_LIBS} ${GRID_LIBS} gtest_dune_xt_common)
+                list(APPEND dxt_test_binaries ${target})
+                set(dxt_test_names_${target} ${testlist_${testbase}_${target}})
+              endforeach(target)
+        else(dune-testtools_FOUND)
+            MESSAGE("-- missing dune-testtools, disabling test ${source}")
+        endif(dune-testtools_FOUND)
     else(EXISTS ${minifile})
       set(target test_${testbase})
       dune_add_test(NAME

dune.module

@@ -14,4 +14,5 @@
 Module: dune-xt-common
 Version: 18.11-dev
 Maintainer: dune-xt-dev@listserv.uni-muenster.de
-Depends: dune-common (>= 2.6) dune-testtools (>= 2.6) dune-pybindxi (>= 18.11) dune-istl (>= 2.6)
+Depends: dune-common (>= 2.6) dune-pybindxi (>= 18.11) dune-istl (>= 2.6)
+Suggests: dune-testttols (>= 2.6)