Fix cannot modify frozen string

Note that Performance/UnfreezeString recommends unary plus over
"".dup, but unary plus has lower precedence so we have to use
parenthesis

spec/lib/banzai/filter/table_of_contents_filter_spec.rb

@@ -114,11 +114,11 @@ describe Banzai::Filter::TableOfContentsFilter do
     context 'table of contents nesting' do
       let(:results) do
         result(
-          header(1, 'Header 1') <<
-          header(2, 'Header 1-1') <<
-          header(3, 'Header 1-1-1') <<
-          header(2, 'Header 1-2') <<
-          header(1, 'Header 2') <<
+          header(1, 'Header 1') +
+          header(2, 'Header 1-1') +
+          header(3, 'Header 1-1-1') +
+          header(2, 'Header 1-2') +
+          header(1, 'Header 2') +
           header(2, 'Header 2-1')
         )
       end

spec/lib/gitlab/auth/o_auth/auth_hash_spec.rb

@@ -15,13 +15,13 @@ describe Gitlab::Auth::OAuth::AuthHash do
   end
 
   let(:uid_raw) do
-    "CN=Onur K\xC3\xBC\xC3\xA7\xC3\xBCk,OU=Test,DC=example,DC=net"
+    +"CN=Onur K\xC3\xBC\xC3\xA7\xC3\xBCk,OU=Test,DC=example,DC=net"
   end
-  let(:email_raw) { "onur.k\xC3\xBC\xC3\xA7\xC3\xBCk_ABC-123@example.net" }
-  let(:nickname_raw) { "ok\xC3\xBC\xC3\xA7\xC3\xBCk" }
-  let(:first_name_raw) { 'Onur' }
-  let(:last_name_raw) { "K\xC3\xBC\xC3\xA7\xC3\xBCk" }
-  let(:name_raw) { "Onur K\xC3\xBC\xC3\xA7\xC3\xBCk" }
+  let(:email_raw) { +"onur.k\xC3\xBC\xC3\xA7\xC3\xBCk_ABC-123@example.net" }
+  let(:nickname_raw) { +"ok\xC3\xBC\xC3\xA7\xC3\xBCk" }
+  let(:first_name_raw) { +'Onur' }
+  let(:last_name_raw) { +"K\xC3\xBC\xC3\xA7\xC3\xBCk" }
+  let(:name_raw) { +"Onur K\xC3\xBC\xC3\xA7\xC3\xBCk" }
 
   let(:uid_ascii) { uid_raw.force_encoding(Encoding::ASCII_8BIT) }
   let(:email_ascii) { email_raw.force_encoding(Encoding::ASCII_8BIT) }

spec/lib/gitlab/ci/trace/chunked_io_spec.rb

@@ -314,7 +314,7 @@ describe Gitlab::Ci::Trace::ChunkedIO, :clean_gitlab_redis_cache do
     end
 
     context 'when utf-8 is being used' do
-      let(:sample_trace_raw) { sample_trace_raw_utf8.force_encoding(Encoding::BINARY) }
+      let(:sample_trace_raw) { sample_trace_raw_utf8.dup.force_encoding(Encoding::BINARY) }
       let(:sample_trace_raw_utf8) { "😺\n😺\n😺\n😺" }
 
       before do

spec/lib/gitlab/encoding_helper_spec.rb

@@ -11,8 +11,8 @@ describe Gitlab::EncodingHelper do
     [
       ["nil", nil, nil],
       ["empty string", "".encode("ASCII-8BIT"), "".encode("UTF-8")],
-      ["invalid utf-8 encoded string", "my bad string\xE5".force_encoding("UTF-8"), "my bad string"],
-      ["frozen non-ascii string", "é".force_encoding("ASCII-8BIT").freeze, "é".encode("UTF-8")],
+      ["invalid utf-8 encoded string", (+"my bad string\xE5").force_encoding("UTF-8"), "my bad string"],
+      ["frozen non-ascii string", (+"é").force_encoding("ASCII-8BIT").freeze, "é".encode("UTF-8")],
       [
         'leaves ascii only string as is',
         'ascii only string',
@@ -25,7 +25,7 @@ describe Gitlab::EncodingHelper do
       ],
       [
         'removes invalid bytes from ASCII-8bit encoded multibyte string. This can occur when a git diff match line truncates in the middle of a multibyte character. This occurs after the second word in this example. The test string is as short as we can get while still triggering the error condition when not looking at `detect[:confidence]`.',
-        "mu ns\xC3\n Lorem ipsum dolor sit amet, consectetur adipisicing ut\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg kia elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non p\n {: .normal_pn}\n \n-Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in\n# *Lorem ipsum\xC3\xB9l\xC3\xB9l\xC3\xA0 dolor\xC3\xB9k\xC3\xB9 sit\xC3\xA8b\xC3\xA8 N\xC3\xA8 amet b\xC3\xA0d\xC3\xAC*\n+# *consectetur\xC3\xB9l\xC3\xB9l\xC3\xA0 adipisicing\xC3\xB9k\xC3\xB9 elit\xC3\xA8b\xC3\xA8 N\xC3\xA8 sed do\xC3\xA0d\xC3\xAC*{: .italic .smcaps}\n \n \xEF\x9B\xA1 eiusmod tempor incididunt, ut\xC3\xAAn\xC3\xB9 labore et dolore. Tw\xC4\x83nj\xC3\xAC magna aliqua. Ut enim ad minim veniam\n {: .normal}\n@@ -9,5 +9,5 @@ quis nostrud\xC3\xAAt\xC3\xB9 exercitiation ullamco laboris m\xC3\xB9s\xC3\xB9k\xC3\xB9abc\xC3\xB9 nisi ".force_encoding('ASCII-8BIT'),
+        (+"mu ns\xC3\n Lorem ipsum dolor sit amet, consectetur adipisicing ut\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg kia elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non p\n {: .normal_pn}\n \n-Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in\n# *Lorem ipsum\xC3\xB9l\xC3\xB9l\xC3\xA0 dolor\xC3\xB9k\xC3\xB9 sit\xC3\xA8b\xC3\xA8 N\xC3\xA8 amet b\xC3\xA0d\xC3\xAC*\n+# *consectetur\xC3\xB9l\xC3\xB9l\xC3\xA0 adipisicing\xC3\xB9k\xC3\xB9 elit\xC3\xA8b\xC3\xA8 N\xC3\xA8 sed do\xC3\xA0d\xC3\xAC*{: .italic .smcaps}\n \n \xEF\x9B\xA1 eiusmod tempor incididunt, ut\xC3\xAAn\xC3\xB9 labore et dolore. Tw\xC4\x83nj\xC3\xAC magna aliqua. Ut enim ad minim veniam\n {: .normal}\n@@ -9,5 +9,5 @@ quis nostrud\xC3\xAAt\xC3\xB9 exercitiation ullamco laboris m\xC3\xB9s\xC3\xB9k\xC3\xB9abc\xC3\xB9 nisi ").force_encoding('ASCII-8BIT'),
         "mu ns\n Lorem ipsum dolor sit amet, consectetur adipisicing ut\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg kia elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non p\n {: .normal_pn}\n \n-Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in\n# *Lorem ipsum\xC3\xB9l\xC3\xB9l\xC3\xA0 dolor\xC3\xB9k\xC3\xB9 sit\xC3\xA8b\xC3\xA8 N\xC3\xA8 amet b\xC3\xA0d\xC3\xAC*\n+# *consectetur\xC3\xB9l\xC3\xB9l\xC3\xA0 adipisicing\xC3\xB9k\xC3\xB9 elit\xC3\xA8b\xC3\xA8 N\xC3\xA8 sed do\xC3\xA0d\xC3\xAC*{: .italic .smcaps}\n \n \xEF\x9B\xA1 eiusmod tempor incididunt, ut\xC3\xAAn\xC3\xB9 labore et dolore. Tw\xC4\x83nj\xC3\xAC magna aliqua. Ut enim ad minim veniam\n {: .normal}\n@@ -9,5 +9,5 @@ quis nostrud\xC3\xAAt\xC3\xB9 exercitiation ullamco laboris m\xC3\xB9s\xC3\xB9k\xC3\xB9abc\xC3\xB9 nisi "
       ],
       [
@@ -95,7 +95,7 @@ describe Gitlab::EncodingHelper do
     [
       ["nil", nil, nil],
       ["empty string", "".encode("ASCII-8BIT"), "".encode("UTF-8")],
-      ["invalid utf-8 encoded string", "my bad string\xE5".force_encoding("UTF-8"), "my bad stringå"],
+      ["invalid utf-8 encoded string", (+"my bad string\xE5").force_encoding("UTF-8"), "my bad stringå"],
       [
         "encodes valid utf8 encoded string to utf8",
         "λ, λ, λ".encode("UTF-8"),
@@ -162,12 +162,12 @@ describe Gitlab::EncodingHelper do
       ],
       [
         'removes invalid bytes from ASCII-8bit encoded multibyte string.',
-        "Lorem ipsum\xC3\n dolor sit amet, xy\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg".force_encoding('ASCII-8BIT'),
+        (+"Lorem ipsum\xC3\n dolor sit amet, xy\xC3\xA0y\xC3\xB9abcd\xC3\xB9efg").force_encoding('ASCII-8BIT'),
         "Lorem ipsum\n dolor sit amet, xyàyùabcdùefg"
       ],
       [
         'handles UTF-16BE encoded strings',
-        "\xFE\xFF\x00\x41".force_encoding('ASCII-8BIT'), # An "A" prepended with UTF-16 BOM
+        (+"\xFE\xFF\x00\x41").force_encoding('ASCII-8BIT'), # An "A" prepended with UTF-16 BOM
         "\xEF\xBB\xBFA" # An "A" prepended with UTF-8 BOM
       ]
     ].each do |description, test_string, xpect|