Remove snapshot content from rspec description

# What
Provide the snapshot file path rather than the contents of the snapshot in rspec description.

The snapshot can be many hundreds/thousands of lines long, and doesn't provide much benefit as the description.

- resolves: levinmr#48

lib/rspec/snapshot/file_operator.rb

@@ -6,6 +6,8 @@ module RSpec
   module Snapshot
     # Handles File IO for snapshots
     class FileOperator
+      attr_reader :snapshot_path
+
       # Initializes the class instance, and creates the snapshot directory for
       # the current test if needed.
       #

lib/rspec/snapshot/matchers/match_snapshot.rb

@@ -48,7 +48,7 @@ def matches?(actual)
         end
 
         def description
-          "to match a snapshot containing: \"#{@expected}\""
+          "to match a snapshot: '#{@file_operator.snapshot_path}'"
         end
 
         def diffable?

spec/rspec/snapshot/matchers/match_snapshot_spec.rb

@@ -79,17 +79,17 @@
   end
 
   describe '.description' do
-    subject { described_class.new(nil, nil) }
+    subject { described_class.new(nil, file_operator) }
 
-    let(:expected) { 'snapshot value' }
+    let(:snapshot_path) { 'path/to/snapshot.snap' }
 
     before do
-      subject.instance_variable_set(:@expected, expected)
+      allow(file_operator).to receive(:snapshot_path).and_return(snapshot_path)
     end
 
-    it 'returns a description of the expected value' do
+    it 'returns a description which includes the path to the snapshot' do
       expect(subject.description).to(
-        eq("to match a snapshot containing: \"#{expected}\"")
+        eq("to match a snapshot: '#{snapshot_path}'")
       )
     end
   end