diff --git a/test/rubygems/test_gem.rb b/test/rubygems/test_gem.rb
index 6d36a8bb629fa5..a7174cf689c2c2 100644
--- a/test/rubygems/test_gem.rb
+++ b/test/rubygems/test_gem.rb
@@ -1254,8 +1254,8 @@ def test_self_try_activate_missing_dep
       Gem.try_activate "a_file"
     end
 
-    assert_match(/Could not find 'b' /, e.message)
-    assert_match(/at: #{a.spec_file}/, e.message)
+    assert_include(e.message, "Could not find 'b' ")
+    assert_include(e.message, "at: #{a.spec_file}")
   end
 
   def test_self_try_activate_missing_prerelease
diff --git a/test/rubygems/test_gem_command_manager.rb b/test/rubygems/test_gem_command_manager.rb
index 6e27e849bcac19..fe7f3da1378823 100644
--- a/test/rubygems/test_gem_command_manager.rb
+++ b/test/rubygems/test_gem_command_manager.rb
@@ -150,7 +150,7 @@ def test_process_args_with_c_flag_without_path
       end
     end
 
-    assert_match(/install isn't a directory./i, @ui.error)
+    assert_match(/install isn't a directory\./i, @ui.error)
   end
 
   def test_process_args_with_c_flag_path_not_found
@@ -164,7 +164,7 @@ def test_process_args_with_c_flag_path_not_found
       end
     end
 
-    assert_match(/#{custom_start_point} isn't a directory./i, @ui.error)
+    assert_match(/#{Regexp.quote(custom_start_point)} isn't a directory\./i, @ui.error)
   end
 
   def test_process_args_bad_arg
@@ -368,7 +368,7 @@ def execute
     end
 
     assert_equal "pew pew!\n", @ui.output
-    assert_match(/WARNING:  foo command is deprecated. It will be removed in Rubygems [0-9]+/, @ui.error)
+    assert_match(/WARNING:  foo command is deprecated\. It will be removed in Rubygems [0-9]+/, @ui.error)
   ensure
     Gem::Commands.send(:remove_const, :FooCommand)
   end
@@ -393,7 +393,7 @@ def execute
     end
 
     assert_equal "pew pew!\n", @ui.output
-    assert_match(/WARNING:  foo command is deprecated. It will be removed in Rubygems 9.9.9/, @ui.error)
+    assert_match(/WARNING:  foo command is deprecated\. It will be removed in Rubygems 9\.9\.9/, @ui.error)
   ensure
     Gem::Commands.send(:remove_const, :FooCommand)
   end
diff --git a/test/rubygems/test_gem_commands_cert_command.rb b/test/rubygems/test_gem_commands_cert_command.rb
index 5249b25c8c22c2..c17346793513e3 100644
--- a/test/rubygems/test_gem_commands_cert_command.rb
+++ b/test/rubygems/test_gem_commands_cert_command.rb
@@ -677,8 +677,9 @@ def test_execute_re_sign
 
     expected_path = File.join(gem_path, "#{File.basename(tmp_expired_cert_file)}.expired")
 
+    assert_include(@ui.output, "INFO:  Your certificate #{tmp_expired_cert_file} has been re-signed\n")
     assert_match(
-      /INFO:  Your certificate #{tmp_expired_cert_file} has been re-signed\nINFO:  Your expired certificate will be located at: #{expected_path}\.[0-9]+/,
+      /INFO:  Your expired certificate will be located at: #{Regexp.quote(expected_path)}\.[0-9]+/,
       @ui.output
     )
     assert_equal "", @ui.error
diff --git a/test/rubygems/test_gem_commands_info_command.rb b/test/rubygems/test_gem_commands_info_command.rb
index 4e2a8f3622676c..83e4c8a8967d94 100644
--- a/test/rubygems/test_gem_commands_info_command.rb
+++ b/test/rubygems/test_gem_commands_info_command.rb
@@ -33,12 +33,12 @@ def test_execute
       @cmd.execute
     end
 
-    assert_match %r{#{@gem.name} \(#{@gem.version}\)\n}, @ui.output
-    assert_match(/Authors: #{@gem.authors.join(', ')}\n/, @ui.output)
-    assert_match(/Homepage: #{@gem.homepage}\n/, @ui.output)
-    assert_match(/License: #{@gem.license}\n/, @ui.output)
-    assert_match(/Installed at: #{@gem.base_dir}\n/, @ui.output)
-    assert_match(/#{@gem.summary}\n/, @ui.output)
+    assert_include(@ui.output, "#{@gem.name} (#{@gem.version})\n")
+    assert_include(@ui.output, "Authors: #{@gem.authors.join(", ")}\n")
+    assert_include(@ui.output, "Homepage: #{@gem.homepage}\n")
+    assert_include(@ui.output, "License: #{@gem.license}\n")
+    assert_include(@ui.output, "Installed at: #{@gem.base_dir}\n")
+    assert_include(@ui.output, "#{@gem.summary}\n")
     assert_match "", @ui.error
   end
 
diff --git a/test/rubygems/test_gem_ext_ext_conf_builder.rb b/test/rubygems/test_gem_ext_ext_conf_builder.rb
index 018251ac069a90..218c6f3d5e3678 100644
--- a/test/rubygems/test_gem_ext_ext_conf_builder.rb
+++ b/test/rubygems/test_gem_ext_ext_conf_builder.rb
@@ -34,7 +34,7 @@ def test_class_build
     assert_same result, output
 
     assert_match(/^current directory:/, output[0])
-    assert_match(/^#{Gem.ruby}.* extconf.rb/, output[1])
+    assert_match(/^#{Regexp.quote(Gem.ruby)}.* extconf.rb/, output[1])
     assert_equal "creating Makefile\n", output[2]
     assert_match(/^current directory:/, output[3])
     assert_contains_make_command "clean", output[4]
@@ -114,7 +114,7 @@ def test_class_build_extconf_fail
 
     assert_equal "extconf failed, exit code 1", error.message
 
-    assert_match(/^#{Gem.ruby}.* extconf.rb/, output[1])
+    assert_match(/^#{Regexp.quote(Gem.ruby)}.* extconf.rb/, output[1])
     assert_match(File.join(@dest_path, "mkmf.log"), output[4])
     assert_includes(output, "To see why this extension failed to compile, please check the mkmf.log which can be found here:\n")
 
diff --git a/test/rubygems/test_gem_installer.rb b/test/rubygems/test_gem_installer.rb
index 71dabe833cb31f..adda63cf22df4e 100644
--- a/test/rubygems/test_gem_installer.rb
+++ b/test/rubygems/test_gem_installer.rb
@@ -738,9 +738,9 @@ def test_generate_bin_uses_default_shebang
       installer.generate_bin
 
       default_shebang = Gem.ruby
-      shebang_line = File.open("#{@gemhome}/bin/executable") {|f| f.readlines.first }
+      shebang_line = File.open("#{@gemhome}/bin/executable", &:gets)
       assert_match(/\A#!/, shebang_line)
-      assert_match(/#{default_shebang}/, shebang_line)
+      assert_include(shebang_line, default_shebang)
     end
   end