Fix failure case for chained matchers (#288)

Fixes #286.

SuperDiff overrides the built-in `RaiseError` matcher to [report that it
is
`diffable?`](https://github.com/splitwise/super_diff/blob/303a5f0d39008ec408d7ab87c5020bdb069558e4/lib/super_diff/rspec/monkey_patches.rb#L836)
in most cases. RSpec accordingly
[assumes](https://github.com/rspec/rspec/blame/a067137e8655e8ee5820a5ebf8ca89054aa9499b/rspec-expectations/lib/rspec/matchers/expecteds_for_multiple_diffs.rb#L37)
that it defines `#expected`. This issue may have existed since
[SuperDiff
0.2.0](0c72106#diff-95eeb68cdb264bd5b96144f59ef69453acfbed67e571cb94d236008a4194217eR414-R416)
and [RSpec
3.2.0](rspec/rspec-expectations@709c8e7#diff-4457c9afedb7030c9af041e6da43bfa3bb2a590b07cb7c64a118486446d3b300R49).

This PR monkey-patches the `#expected` assumption, much in the same way
that we [already
do](https://github.com/splitwise/super_diff/blob/8645b956aa1c43dbde50445b4b99f6fc9504a14a/lib/super_diff/rspec/monkey_patches.rb#L29-L34)
for `#handle_failure`.

Author: jas14

CHANGELOG.md

@@ -16,6 +16,7 @@
 
 - Fix ActiveRecord's `attributes_for_super_diff` and tree builders related to Active Records to handle models that do not have a primary key.
   [#282](https://github.com/splitwise/super_diff/pull/282) by [@atranson-electra](https://github.com/atranson-electra)
+- Fix failure case for chained matchers. [#288](https://github.com/splitwise/super_diff/pull/288)
 
 ### Other changes
 

docs/contributors/architecture/how-super-diff-works.md

@@ -39,7 +39,8 @@ or when a matcher whose `#does_not_match?` method returns `true`
 is passed to `expect(...).not_to` —
 RSpec will call the `RSpec::Expectations::ExpectationHelper#handle_failure` method,
 which will call `RSpec::Expectations.fail_with`.
-This method will use `RSpec::Matchers::ExpectedsForMultipleDiffs`
+This method will use `RSpec::Matchers::MultiMatcherDiff`
+(or in RSpec < 3.13.0, `RSpec::Matchers::ExpectedsForMultipleDiffs`)
 and the differ object that `RSpec::Expectations.differ` returns
 to generate a diff,
 combining it with the failure message from the matcher,
@@ -89,7 +90,7 @@ Here are all of the places that SuperDiff patches RSpec:
   as it interferes with the previous patches)
 - `RSpec::Support::ObjectFormatter`
   (to use SuperDiff's object inspection logic)
-- `RSpec::Matchers::ExpectedsForMultipleDiffs`
+- `RSpec::Matchers::ExpectedsForMultipleDiffs` and `RSpec::Matchers::MultiMatcherDiff`
   (to add a key above the diff,
   add spacing around the diff,
   and colorize the word "Diff:")

lib/super_diff/rspec/monkey_patches.rb

@@ -352,6 +352,26 @@ def from(expected)
             new([[expected, text]])
           end
 
+          def for_many_matchers(matchers)
+            # Look for expected_for_diff and actual_for_diff if possible
+            diff_tuples = matchers.map do |m|
+              expected = if m.respond_to?(:expected_for_diff)
+                           m.expected_for_diff
+                         else
+                           m.expected
+                         end
+
+              actual = if m.respond_to?(:actual_for_diff)
+                         m.actual_for_diff
+                       else
+                         m.actual
+                       end
+              [expected, diff_label_for(m), actual]
+            end
+
+            new(diff_tuples)
+          end
+
           def colorizer
             RSpec::Core::Formatters::ConsoleCodes
           end
@@ -423,6 +443,26 @@ def from(expected, actual)
             new([[expected, text, actual]])
           end
 
+          def for_many_matchers(matchers)
+            # Look for expected_for_diff and actual_for_diff if possible
+            diff_tuples = matchers.map do |m|
+              expected = if m.respond_to?(:expected_for_diff)
+                           m.expected_for_diff
+                         else
+                           m.expected
+                         end
+
+              actual = if m.respond_to?(:actual_for_diff)
+                         m.actual_for_diff
+                       else
+                         m.actual
+                       end
+              [expected, diff_label_for(m), actual]
+            end
+
+            new(diff_tuples)
+          end
+
           def colorizer
             RSpec::Core::Formatters::ConsoleCodes
           end

spec/integration/rspec/raise_error_matcher_spec.rb

@@ -1487,4 +1487,39 @@
       end
     end
   end
+
+  context 'when part of an expectation chain' do
+    context 'when the expected error and/or actual message is short' do
+      it 'produces the correct failure message' do
+        as_both_colored_and_uncolored do |color_enabled|
+          snippet = <<~TEST.strip
+            expect { raise StandardError.new('boo') }.to raise_error(RuntimeError, 'bar').and(change(Random, :rand))
+          TEST
+          program =
+            make_plain_test_program(snippet, color_enabled: color_enabled)
+
+          expected_output =
+            build_expected_output(
+              color_enabled: color_enabled,
+              snippet:
+                "expect { raise StandardError.new('boo') }.to raise_error(RuntimeError, 'bar').and(change(Random, :rand))",
+              expectation:
+                proc do
+                  line do
+                    plain 'Expected raised exception '
+                    actual %(#<StandardError "boo">)
+                    plain ' to match '
+                    expected 'a kind of RuntimeError with message "bar"'
+                    plain '.'
+                  end
+                end
+            )
+
+          expect(program).to produce_output_when_run(
+            expected_output
+          ).in_color(color_enabled)
+        end
+      end
+    end
+  end
 end