Support label for aggregate_failures block

spec/spectator/aggregate_failures_spec.cr

@@ -28,5 +28,14 @@ Spectator.describe Spectator do
         end
       end.to_not raise_error(Spectator::ExpectationFailed)
     end
+
+    it "supports naming the block" do
+      expect do
+        aggregate_failures "contradiction" do
+          expect(true).to be_false
+          expect(false).to be_true
+        end
+      end.to raise_error(Spectator::MultipleExpectationsFailed, /contradiction/)
+    end
   end
 end

src/spectator/dsl/expectations.cr

@@ -172,8 +172,8 @@ module Spectator::DSL
     #  expect(false).to be_true
     # end
     # ```
-    def aggregate_failures
+    def aggregate_failures(label = nil)
-      ::Spectator::Harness.current.aggregate_failures do
+      ::Spectator::Harness.current.aggregate_failures(label) do
         yield
       end
     end

src/spectator/harness.cr

@@ -100,20 +100,20 @@ module Spectator
       @deferred << block
     end
 
-    def aggregate_failures
+    def aggregate_failures(label = nil)
       previous = @aggregate
       @aggregate = aggregate = [] of Expectation
       begin
         yield.tap do
           # If there's an nested aggregate (for some reason), allow the top-level one to handle things.
-          check_aggregate(aggregate) unless previous
+          check_aggregate(aggregate, label) unless previous
         end
       ensure
         @aggregate = previous
       end
     end
 
-    private def check_aggregate(aggregate)
+    private def check_aggregate(aggregate, label)
       failures = aggregate.select(&.failed?)
       case failures.size
       when 0 then return
@@ -121,7 +121,9 @@ module Spectator
         expectation = failures.first
         raise ExpectationFailed.new(expectation, expectation.failure_message)
       else
-        raise MultipleExpectationsFailed.new(failures, "Got #{failures.size} failures from failure aggregation block")
+        message = "Got #{failures.size} failures from failure aggregation block"
+        message += " \"#{label}\"" if label
+        raise MultipleExpectationsFailed.new(failures, message)
       end
     end