Prevent invalid encoding for files blowing up

lib/rspec/support/source.rb

@@ -14,13 +14,17 @@ class Source
       # stubbed out within tests.
       class File
         class << self
-          [:read, :expand_path].each do |method_name|
+          [:binread, :read, :expand_path].each do |method_name|
             define_method(method_name, &::File.method(method_name))
           end
         end
       end
 
       def self.from_file(path)
+        # We must use `binread` here, there is no spec for this behaviour
+        # as its proven troublesome to replicate within our spec suite, but
+        # to manually verify run:
+        # `bundle exec rspec spec/support/source_broken_example`
         source = File.read(path)
         new(source, path)
       end

spec/support/source_broken_example

@@ -0,0 +1,8 @@
+Encoding.default_internal = Encoding::BINARY
+
+describe UndeclaredModule do
+  # the missing constant can be anything
+  it 'crashes and does not even parse this' do
+    'привет'
+  end
+end