1 files changed, 45 insertions, 3 deletions
diff --git a/spec/ruby/core/kernel/inspect_spec.rb b/spec/ruby/core/kernel/inspect_spec.rb
index e60f7576c5..8fc3ab51cd 100644
--- a/spec/ruby/core/kernel/inspect_spec.rb
+++ b/spec/ruby/core/kernel/inspect_spec.rb
@@ -3,7 +3,7 @@ require_relative 'fixtures/classes'
 
 describe "Kernel#inspect" do
   it "returns a String" do
-    Object.new.inspect.should be_an_instance_of(String)
+    Object.new.inspect.should.instance_of?(String)
   end
 
   it "does not call #to_s if it is defined" do
@@ -26,10 +26,10 @@ describe "Kernel#inspect" do
     class << obj
       undef_method :class
     end
-    obj.inspect.should be_kind_of(String)
+    obj.inspect.should.is_a?(String)
   end
 
-  ruby_version_is "3.5" do
+  ruby_version_is "4.0" do
     it "calls #instance_variables_to_inspect private method to know which variables to display" do
       obj = Object.new
       obj.instance_eval do
@@ -57,5 +57,47 @@ describe "Kernel#inspect" do
       inspected = obj.inspect.sub(/^#<Object:0x[0-9a-f]+/, '#<Object:0x00')
       inspected.should == "#<Object:0x00>"
     end
+
+    it "displays all instance variables if #instance_variables_to_inspect returns nil" do
+      obj = Object.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      obj.singleton_class.class_eval do
+        private def instance_variables_to_inspect = nil
+      end
+
+      inspected = obj.inspect.sub(/^#<Object:0x[0-9a-f]+/, '#<Object:0x00')
+      inspected.should ==  %{#<Object:0x00 @host="localhost", @user="root", @password="hunter2">}
+    end
+
+    it "displays all instance variables if #instance_variables_to_inspect is not defined" do
+      obj = BasicObject.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      method_inspect = Kernel.instance_method(:inspect)
+
+      inspected = method_inspect.bind(obj).call.sub(/^#<BasicObject:0x[0-9a-f]+/, '#<BasicObject:0x00')
+      inspected.should ==  %{#<BasicObject:0x00 @host="localhost", @user="root", @password="hunter2">}
+    end
+
+    it "raises an error if #instance_variables_to_inspect returns an invalid value" do
+      obj = Object.new
+      obj.instance_eval do
+        @host = "localhost"
+        @user = "root"
+        @password = "hunter2"
+      end
+      obj.singleton_class.class_eval do
+        private def instance_variables_to_inspect = {}
+      end
+
+      ->{ obj.inspect }.should.raise(TypeError, "Expected #instance_variables_to_inspect to return an Array or nil, but it returned Hash")
+    end
   end
 end