[CMake] Conditionally enable FUSE and HTTP tests

FUSE may be installed, but not mounted, and davix commands
may not be available. The two new switches allows disabling
these tests if dependencies are not satisfied.

cmake/XRootDFindLibs.cmake

@@ -70,19 +70,6 @@ if( ENABLE_FUSE AND (LINUX OR KFREEBSD) )
   endif()
 endif()
 
-if( ENABLE_TESTS )
-  if( FORCE_ENABLED )
-    find_package( GTest REQUIRED )
-  else()
-    find_package( GTest )
-  endif()
-  if( GTEST_FOUND )
-    set( BUILD_TESTS TRUE )
-  else()
-    set( BUILD_TESTS FALSE )
-  endif()
-endif()
-
 if( ENABLE_HTTP )
   set( BUILD_HTTP TRUE )
   if( CURL_FOUND )
@@ -214,3 +201,26 @@ if( ENABLE_XRDCLHTTP )
     set( BUILD_XRDCLHTTP FALSE )
   endif()
 endif()
+
+if( ENABLE_TESTS )
+  if( FORCE_ENABLED )
+    find_package( GTest REQUIRED )
+  else()
+    find_package( GTest )
+  endif()
+  if( GTEST_FOUND )
+    set( BUILD_TESTS TRUE )
+  else()
+    set( BUILD_TESTS FALSE )
+  endif()
+
+  if( ENABLE_SERVER_TESTS )
+    if( BUILD_FUSE AND EXISTS "/dev/fuse" )
+      set(ENABLE_FUSE_TESTS TRUE CACHE BOOL "Enable FUSE tests")
+    endif()
+
+    if( BUILD_HTTP AND BUILD_XRDCLHTTP )
+      set(ENABLE_HTTP_TESTS TRUE CACHE BOOL "Enable HTTP tests")
+    endif()
+  endif()
+endif()

tests/XRootD/CMakeLists.txt

@@ -1,11 +1,11 @@
 
 list(APPEND XROOTD_CONFIGS noauth host unix sss)
 
-if(BUILD_FUSE)
+if(ENABLE_FUSE_TESTS)
   list(APPEND XROOTD_CONFIGS fuse)
 endif()
 
-if(BUILD_HTTP)
+if(ENABLE_HTTP_TESTS)
   list(APPEND XROOTD_CONFIGS http)
 endif()