Prevent invalid encoding for files blowing up

lib/rspec/support/source.rb

@@ -11,6 +11,11 @@ class Source
       def self.from_file(path)
         source = File.read(path)
         new(source, path)
+      # There is no spec for this behaviour as its proven troublesome to
+      # replicate within our spec suite, to manually verify run
+      # `bundle exec rspec spec/support/source_spec.broken_example`
+      rescue Encoding::UndefinedConversionError
+        new("", path)
       end
 
       if String.method_defined?(:encoding)

spec/support/source_spec.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
+    header = 'привет'
+  end
+end