test/test_utils.rb in tzinfo-1.2.4 vs test/test_utils.rb in tzinfo-1.2.5

@@ -58,11 +58,40 @@
     # JRuby and Rubinus don't support SAFE levels.
     available = !(defined?(RUBY_ENGINE) && %w(jruby rbx).include?(RUBY_ENGINE))
    
     if available || options[:unavailable] != :skip
       thread = Thread.new do
-        $SAFE = options[:level] || 1 if available
-        yield
+        orig_diff = Minitest::Assertions.diff
+
+        if available
+          orig_safe = $SAFE
+          $SAFE = options[:level] || 1
+        end
+        begin
+          # Disable the use of external diff tools during safe mode tests (since
+          # safe mode will prevent their use). The initial value is retrieved
+          # before activating safe mode because the first time
+          # Minitest::Assertions.diff is called, it will attempt to find a diff
+          # tool. Finding the diff tool will also fail in safe mode.
+          Minitest::Assertions.diff = nil
+          begin
+            yield
+          ensure
+            Minitest::Assertions.diff = orig_diff
+          end
+        ensure
+          if available
+            # On Ruby < 2.6, setting $SAFE affects only the current thread
+            # and the $SAFE level cannot be downgraded. Catch and ignore the
+            # SecurityError.
+            # On Ruby >= 2.6, setting $SAFE is global, and the $SAFE level
+            # can be downgraded. Restore $SAFE back to the original level.
+            begin
+              $SAFE = orig_safe
+            rescue SecurityError
+            end
+          end
+        end
       end
       
       thread.join
     end
   end