Keep all errors for all union types and attach the schema name

..So not only the errors from the first failed union type are kept

lang/ruby/lib/avro/schema_validator.rb

@@ -196,9 +196,14 @@ def validate_union(expected_schema, datum, path, result, options)
         compatible_type = first_compatible_type(datum, expected_schema, path, failures, options)
         return unless compatible_type.nil?
 
-        complex_type_failed = failures.detect { |r| COMPLEX_TYPES.include?(r[:type]) }
-        if complex_type_failed
-          complex_type_failed[:result].errors.each { |error| result << error }
+        complex_type_failed = failures.select { |r| COMPLEX_TYPES.include?(r[:type]) }
+        if complex_type_failed.any?
+          complex_type_failed.each do |type_failures|
+            type_failures[:result].errors.each do |error|
+              error_msg = type_failures[:schema] ? "#{type_failures[:schema]} #{error}" : error
+              result << error_msg
+            end
+          end
         else
           types = expected_schema.schemas.map { |s| "'#{s.type_sym}'" }.join(', ')
           result.add_error(path, "expected union of [#{types}], got #{actual_value_message(datum)}")
@@ -208,11 +213,16 @@ def validate_union(expected_schema, datum, path, result, options)
       def first_compatible_type(datum, expected_schema, path, failures, options = {})
         expected_schema.schemas.find do |schema|
           # Avoid expensive validation if we're just validating a nil
-          next datum.nil? if schema.type_sym == :null
+          if schema.type_sym == :null
+            next datum.nil?
+          end
 
           result = Result.new
           validate_recursive(schema, datum, path, result, options)
-          failures << { type: schema.type_sym, result: result } if result.failure?
+
+          failure = { type: schema.type_sym, result: result }
+          failure[:schema] = schema.name if schema.is_a?(Avro::Schema::RecordSchema)
+          failures << failure if result.failure?
           !result.failure?
         end
       end

lang/ruby/test/test_schema_validator.rb

@@ -556,7 +556,7 @@ def test_validate_union_extra_fields
       validate!(schema, { 'name' => 'apple', 'color' => 'green' }, fail_on_extra_fields: true)
     end
     assert_equal(1, exception.result.errors.size)
-    assert_equal("at . extra field 'color' - not in schema", exception.to_s)
+    assert_equal("fruit at . extra field 'color' - not in schema", exception.to_s)
   end
 
   def test_validate_bytes_decimal