diff --git a/t/CMDTEST_stdxxx_equal.rb b/t/CMDTEST_stdxxx_equal.rb
index f1a7355..38033ff 100644
--- a/t/CMDTEST_stdxxx_equal.rb
+++ b/t/CMDTEST_stdxxx_equal.rb
@@ -211,6 +211,41 @@ class CMDTEST_stdxxx_equal < Cmdtest::Testcase
       end
     end
 
+    #----------------------------------------
+
+    ## methods: test_stdout_equal_DIFF test_stderr_equal_DIFF
+
+    define_method("test_#{stdxxx}_equal_NO_DIFF") do
+
+      create_CMDTEST_foo [
+        "cmd 'echo_#{stdxxx}.rb --lines 11 33 44 55-changed 66 77 88' do",
+        "    #{stdxxx}_equal [ '11', '22', '33', '44', '55', '66', '77' ]",
+        "end",
+      ]
+
+      cmd_cmdtest_no_diff do
+        stdout_equal [
+          "### echo_#{stdxxx}.rb --lines 11 33 44 55-changed 66 77 88",
+          "--- ERROR: wrong #{stdxxx}",
+          "---        actual: 11",
+          "---                33",
+          "---                44",
+          "---                55-changed",
+          "---                66",
+          "---                77",
+          "---                88",
+          "---        expect: 11",
+          "---                22",
+          "---                33",
+          "---                44",
+          "---                55",
+          "---                66",
+          "---                77",
+        ]
+        exit_nonzero
+      end
+    end
+
     #----------------------------------------
     # stdxxx_not_equal
     #----------------------------------------
diff --git a/t/selftest_utils.rb b/t/selftest_utils.rb
index 4fb9e9e..421640d 100644
--- a/t/selftest_utils.rb
+++ b/t/selftest_utils.rb
@@ -59,6 +59,15 @@ module SelftestUtils
     end
   end
 
+  def cmd_cmdtest_no_diff(*args)
+    cmdtest = "#{TOP}/bin/cmdtest.rb"
+    command = "ruby %s --quiet --no-diff" % _quote(cmdtest)
+    cmd(command, *args) do
+      comment "running local cmdtest --no-diff"
+      yield
+    end
+  end
+
   def cmd_cmdtest_verbose(*args)
     cmdtest = "#{TOP}/bin/cmdtest.rb"
     command = "ruby %s %s" % [