cmake build: Fix handling of test dependencies

Test dependencies are not "real" code dependencies, they just
declare that for testing the plugin the other plugin has to
be loaded, even though it is _not_ a code dependency.

Add PLUGIN_TEST_DEPENDS to add_qtc_plugin. We cannot assume
that the target exists at that point, so adapt the usual pattern.

Fixes: QTCREATORBUG-25024
Change-Id: I4165ff8df762309e0be0bfe9e8bedef796a3bf17
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

cmake/QtCreatorAPI.cmake

@@ -277,7 +277,7 @@ function(add_qtc_plugin target_name)
   cmake_parse_arguments(_arg
     "SKIP_DEBUG_CMAKE_FILE_CHECK;SKIP_INSTALL;INTERNAL_ONLY;SKIP_TRANSLATION;EXPORT"
     "VERSION;COMPAT_VERSION;PLUGIN_JSON_IN;PLUGIN_PATH;PLUGIN_NAME;OUTPUT_NAME;BUILD_DEFAULT"
-    "CONDITION;DEPENDS;PUBLIC_DEPENDS;DEFINES;PUBLIC_DEFINES;INCLUDES;PUBLIC_INCLUDES;SOURCES;EXPLICIT_MOC;SKIP_AUTOMOC;EXTRA_TRANSLATIONS;PLUGIN_DEPENDS;PLUGIN_RECOMMENDS;PROPERTIES"
+    "CONDITION;DEPENDS;PUBLIC_DEPENDS;DEFINES;PUBLIC_DEFINES;INCLUDES;PUBLIC_INCLUDES;SOURCES;EXPLICIT_MOC;SKIP_AUTOMOC;EXTRA_TRANSLATIONS;PLUGIN_DEPENDS;PLUGIN_RECOMMENDS;PLUGIN_TEST_DEPENDS;PROPERTIES"
     ${ARGN}
   )
 
@@ -363,6 +363,15 @@ function(add_qtc_plugin target_name)
       "        { \"Name\" : \"${i}\", \"Version\" : \"${_v}\", \"Type\" : \"optional\" }"
     )
   endforeach(i)
+  foreach(i IN LISTS _arg_PLUGIN_TEST_DEPENDS)
+    if (i MATCHES "^QtCreator::")
+      string(REPLACE "QtCreator::" "" i ${i})
+    endif()
+    set(_v ${IDE_VERSION})
+    string(APPEND _arg_DEPENDENCY_STRING
+      "        { \"Name\" : \"${i}\", \"Version\" : \"${_v}\", \"Type\" : \"test\" }"
+    )
+  endforeach(i)
 
   string(REPLACE "}        {" "},\n        {"
     _arg_DEPENDENCY_STRING "${_arg_DEPENDENCY_STRING}"