Binary string literals in Ruby 2.0

Question

When upgrading to Ruby 2.0, a test case started to fail: ``` expected = "\xD1\x9B\x86" assert_equal expected, actual ``` with the following message: ``` <"ћ\x86"> expected but was <"\xD1\x9B\x86">. ``` The `actual` variable contains a binary string obtained from an external library call. The problem is that the default encoding of source files (and therefore string literals) changed in Ruby 2.0 from US-ASCII to UTF-8.

Accepted Answer

The solution is to change the definition of the string literal to enforce its encoding. There are a few possible options to do this:

Use Array#pack (all versions of Ruby):

```
expected = ["d19b86"].pack('H*')
```

Use String#b (Ruby >= 2.0 only):

```
expected = "\xD1\x9B\x86".b
```

Use String#force_encoding (Ruby >= 1.9 only):

```
expected = "\xD1\x9B\x86".force_encoding("ASCII-8BIT")
```

Binary string literals in Ruby 2.0

Solution

Problem