Truffle's autoload works like Ruby's

But Truffle has its own binding_of_caller equivalent

core_gem/lib/deep_cover/base.rb

@@ -8,7 +8,7 @@ def running?
 
     def start
       return if running?
-      if RUBY_VERSION >= '2.3.0' && RUBY_PLATFORM != 'java'
+      if RUBY_VERSION >= '2.3.0' && on_mri?
         require_relative 'core_ext/instruction_sequence_load_iseq'
       else
         require_relative 'core_ext/autoload_overrides'

core_gem/lib/deep_cover/core_ext/autoload_overrides.rb

@@ -84,7 +84,7 @@ module DeepCover
   load_all
 
   module KernelAutoloadOverride
-    if RUBY_PLATFORM == 'java'
+    if DeepCover.on_jruby?
       # JRuby has different semantics for Kernel.autoload and Kernel#autoload
       def autoload(name, path)
         if Kernel.equal?(self)
@@ -99,6 +99,12 @@ def autoload(name, path)
         autoload_path = DeepCover.autoload_tracker.autoload_path_for(mod, name, path)
         mod.autoload_without_deep_cover(name, autoload_path)
       end
+    elsif DeepCover.on_truffleruby?
+      def autoload(name, path)
+        mod = Truffle.invoke_primitive(:caller_binding).eval('Module.nesting').first || Object
+        autoload_path = DeepCover.autoload_tracker.autoload_path_for(mod, name, path)
+        mod.autoload_without_deep_cover(name, autoload_path)
+      end
     else
       def autoload(name, path)
         mod = binding.of_caller(1).eval('Module.nesting').first || Object

core_gem/spec/deep_cover_spec.rb

@@ -5,7 +5,7 @@
 RSpec.describe DeepCover do
   describe 'cover' do
     after { DeepCover.reset }
-    it 'temporarily overrides (or not in 2.3 +) `require`, `require_relative` and `autoload`' do
+    it 'temporarily overrides (or not in MRI 2.3+) `require`, `require_relative` and `autoload`' do
       methods = %i[require require_relative]
       methods << :autoload unless RUBY_PLATFORM == 'java'
       original = methods.map { |m| method(m).source_location }
@@ -15,11 +15,11 @@
           sources = methods.map { |m| method(m).source_location }
         end
         sources.zip(original).each do |now, before|
-          if RUBY_VERSION < '2.3.0' || RUBY_PLATFORM == 'java'
-            now.should_not == before
-          else
+          if RUBY_VERSION >= '2.3.0' && DeepCover.on_mri?
             # We use load_iseq in 2.3+, so no override in that case
             now.should == before
+          else
+            now.should_not == before
           end
         end
         methods.map { |m| method(m).source_location }.should == original