1 files changed, 32 insertions, 0 deletions
diff --git a/lua/clever_f/testing/memory_host.lua b/lua/clever_f/testing/memory_host.lua
index 459c9a8..0f8fc2d 100644
--- a/lua/clever_f/testing/memory_host.lua
+++ b/lua/clever_f/testing/memory_host.lua
@@ -663,6 +663,38 @@ function MemoryHost:highlight_groups()
   return copy(self._highlight_groups)
 end
 
+function MemoryHost:define_highlight_group(name, definition, options)
+  if type(name) ~= "string" or name == "" then
+    error("highlight group name must be a nonempty string", 2)
+  end
+  if type(definition) ~= "table" then
+    error("highlight group definition must be a table", 2)
+  end
+  options = options or {}
+  if type(options) ~= "table" then
+    error("highlight group options must be a table", 2)
+  end
+  if options.default ~= nil and type(options.default) ~= "boolean" then
+    error("highlight group default option must be a Boolean", 2)
+  end
+  if options.force ~= nil and type(options.force) ~= "boolean" then
+    error("highlight group force option must be a Boolean", 2)
+  end
+
+  local exists = self._highlight_groups[name] ~= nil
+  local applied = not (exists and options.default)
+  if applied then
+    self._highlight_groups[name] = copy(definition)
+  end
+  self:_record("define_highlight_group", {
+    name = name,
+    definition = definition,
+    options = options,
+    applied = applied,
+  })
+  return applied
+end
+
 function MemoryHost:create_highlight(specification)
   if type(specification) ~= "table" then
     error("highlight specification must be a table", 2)