Remove obsolete 'nested' code

We tried testing setting an object value under the new 'flattened
attributes' structure, and the object was only ever being set as
`{}`. This is because we had special case handling for type "object"
which is no longer necessary - we blindly set the value to the
object, no type casting necessary.

We also no longer have the concept of a nested 'validations' or nested 'schema'
property on a nested attribute. All validations are declared at
the root level now and can incorporate multiple attributes, as
we're doing with topical event date validation:
https://github.com/alphagov/whitehall/blob/25addb1ce63d150731560b7a99efc89e731ecf21/app/models/configurable_document_types/topical_event.json#L60-L62

Author: ChrisBAshton

app/models/standard_edition/block_content.rb

@@ -4,7 +4,6 @@ class StandardEdition::BlockContent
   include DateValidation
 
   validate :valid_instance_of_document_type_attributes
-  validate :valid_nested_attributes
 
   VALIDATORS = {
     "embedded_contacts_exist" => GovspeakContactEmbedValidator,
@@ -26,11 +25,7 @@ def attributes=(values)
     values = values.to_h
     @attributes_config.each do |key, nested_schema|
       setter = "#{key}="
-      if nested_schema["type"] == "object"
-        nested_attributes = self.class.new(nested_schema, @path.push(key))
-        nested_attributes.assign_attributes(values[key])
-        public_send(setter, nested_attributes)
-      elsif nested_schema["type"] == "date"
+      if nested_schema["type"] == "date"
         public_send(setter, pre_validate_date_attribute(key, values[key]))
       else
         public_send(setter, values[key])
@@ -57,19 +52,6 @@ def valid_instance_of_document_type_attributes
     end
   end
 
-  def valid_nested_attributes
-    @attributes_config.each do |key, nested_schema|
-      next unless nested_schema["type"] == "object"
-
-      nested_attribute_values = attributes.public_send(key)
-      next if nested_attribute_values.valid?
-
-      nested_attribute_values.errors.each do |error|
-        errors.import(error, { attribute: "#{@path.push(key).validation_error_attribute}.#{error.attribute}" })
-      end
-    end
-  end
-
   def method_missing(symbol, *args)
     if attributes.class.instance_methods.include?(symbol)
       attributes.public_send(symbol, *args)

test/unit/app/models/standard_edition_block_content_merge_test.rb

@@ -115,6 +115,7 @@ class StandardEditionBlockContentMergeTest < ActiveSupport::TestCase
           "body" => { "type" => "string" },
           "summary" => { "type" => "string" },
           "audience" => { "type" => "string" },
+          "meta" => { "type" => "object" },
           "count" => { "type" => "integer" },
         },
       },
@@ -128,6 +129,11 @@ class StandardEditionBlockContentMergeTest < ActiveSupport::TestCase
         "body" => "Start",
         "summary" => "old summary",
         "audience" => "public",
+        "meta" => {
+          "info" => "some info",
+          "details" => "some details",
+          "bool" => true,
+        },
         "count" => 1,
         "junk" => "should be removed", # invalid per schema
       },
@@ -137,9 +143,14 @@ class StandardEditionBlockContentMergeTest < ActiveSupport::TestCase
     params = ActionController::Parameters.new(
       "block_content" => {
         "summary" => "new summary", # overwrite nested valid key
-        "count" => 2,                        # overwrite nested-nested valid key
-        "invalid_nested" => "ignore me",     # invalid nested key
+        "count" => 2, # overwrite nested-nested valid key
+        "invalid_nested" => "ignore me", # invalid nested key
         "unknown" => "ignore me too", # invalid nested key at level 1
+        "meta" => {
+          "info" => "updated info",
+          "details" => "updated details",
+          "bool" => false,
+        },
         "not_in_schema" => "nope", # invalid top-level key
       },
     ).permit!
@@ -155,6 +166,12 @@ class StandardEditionBlockContentMergeTest < ActiveSupport::TestCase
     assert_equal "public",      bc["audience"] # preserved
     assert_equal 2,             bc["count"]    # updated
 
+    assert_equal({
+      "info" => "updated info",
+      "details" => "updated details",
+      "bool" => false,
+    }, bc["meta"].to_h)
+
     # invalid keys filtered out
     assert_nil bc["junk"]
     assert_nil bc["unknown"]

test/unit/app/models/standard_edition_test.rb

@@ -156,29 +156,40 @@ class StandardEditionTest < ActiveSupport::TestCase
     configurable_document_type =
       build_configurable_document_type(
         test_type, {
-          "schema" => {
-            "attributes" => {
-              "test_object_attribute" => {
-                "type" => "object",
-                "attributes" => {
-                  "test_nested_attribute" => {
-                    "type" => "string",
-                  },
-                },
-                "validations" => {
-                  "presence" => {
-                    "attributes" => %w[test_nested_attribute],
+          "forms" => {
+            "documents" => {
+              "fields" => {
+                "test_object_attribute" => {
+                  "title" => "Test object attribute",
+                  "block" => "default_object",
+                  "fields" => {
+                    "test_nested_attribute" => {
+                      "title" => "Test nested attribute",
+                      "block" => "default_string",
+                    },
                   },
                 },
               },
             },
           },
+          "schema" => {
+            "attributes" => {
+              "test_nested_attribute" => {
+                "type" => "string",
+              },
+            },
+            "validations" => {
+              "presence" => {
+                "attributes" => %w[test_nested_attribute],
+              },
+            },
+          },
         }
       )
     ConfigurableDocumentType.setup_test_types(configurable_document_type)
-    page = build(:standard_edition, { configurable_document_type: test_type, block_content: { test_object_attribute: { test_nested_attribute: "" } } })
+    page = build(:standard_edition, { configurable_document_type: test_type, block_content: { test_nested_attribute: "" } })
     assert page.invalid?
-    assert_not page.errors.where("test_object_attribute.test_nested_attribute", :blank).empty?
+    assert_not page.errors.where("test_nested_attribute", :blank).empty?
   end
 
   test "it allows translations if the configurable document type settings permit them" do