From bac19c03f83cb46e4962df01372ce63c43f4aa69 Mon Sep 17 00:00:00 2001
From: Justin Searls <searls@gmail.com>
Date: Fri, 7 Jul 2023 09:52:00 -0400
Subject: [PATCH] Add PluginSupport module

---
 lib/standard.rb                               |  1 +
 lib/standard/plugin_support.rb                |  1 +
 .../merges_upstream_metadata.rb               | 23 +++++++
 .../merges_upstream_metadata_test.rb          | 67 +++++++++++++++++++
 4 files changed, 92 insertions(+)
 create mode 100644 lib/standard/plugin_support.rb
 create mode 100644 lib/standard/plugin_support/merges_upstream_metadata.rb
 create mode 100644 test/standard/plugin_support/merges_upstream_metadata_test.rb

diff --git a/lib/standard.rb b/lib/standard.rb
index ac476341..8f4ac948 100644
--- a/lib/standard.rb
+++ b/lib/standard.rb
@@ -13,3 +13,4 @@ module Standard
 require "standard/formatter"
 
 require "standard/plugin"
+require "standard/plugin_support"
diff --git a/lib/standard/plugin_support.rb b/lib/standard/plugin_support.rb
new file mode 100644
index 00000000..d0414ada
--- /dev/null
+++ b/lib/standard/plugin_support.rb
@@ -0,0 +1 @@
+require "standard/plugin_support/merges_upstream_metadata"
diff --git a/lib/standard/plugin_support/merges_upstream_metadata.rb b/lib/standard/plugin_support/merges_upstream_metadata.rb
new file mode 100644
index 00000000..952387fd
--- /dev/null
+++ b/lib/standard/plugin_support/merges_upstream_metadata.rb
@@ -0,0 +1,23 @@
+module Standard
+  module PluginSupport
+    class MergesUpstreamMetadata
+      def merge(plugin_yaml, upstream_yaml)
+        common_upstream_values = upstream_yaml.select { |key| plugin_yaml.key?(key) }
+
+        plugin_yaml.merge(common_upstream_values) { |key, plugin_value, upstream_value|
+          if plugin_value.is_a?(Hash) && upstream_value.is_a?(Hash)
+            plugin_value.merge(upstream_value) { |sub_key, plugin_sub_value, upstream_sub_value|
+              if plugin_value.key?(sub_key)
+                plugin_sub_value
+              else
+                upstream_sub_value
+              end
+            }
+          else
+            plugin_value
+          end
+        }
+      end
+    end
+  end
+end
diff --git a/test/standard/plugin_support/merges_upstream_metadata_test.rb b/test/standard/plugin_support/merges_upstream_metadata_test.rb
new file mode 100644
index 00000000..a73809ea
--- /dev/null
+++ b/test/standard/plugin_support/merges_upstream_metadata_test.rb
@@ -0,0 +1,67 @@
+require "test_helper"
+
+module Standard
+  module PluginSupport
+    class MergesUpstreamMetadataTest < Minitest::Test
+      def setup
+        @subject = MergesUpstreamMetadata.new
+      end
+
+      def test_no_op
+        assert_equal({}, @subject.merge({}, {}))
+        assert_equal({}, @subject.merge({}, {:junk => {}, "Some/Rule" => {}}))
+        assert_equal({foo: "berry"}, @subject.merge({foo: "berry"}, {:junk => {}, "Some/Rule" => {}}))
+      end
+
+      def test_merges_undefined_sub_keys
+        assert_equal(
+          {"Some/Rule" => {"Enabled" => true, "Description" => "foo"}},
+          @subject.merge(
+            {"Some/Rule" => {"Enabled" => true}},
+            {"Some/Rule" => {"Description" => "foo"}}
+          )
+        )
+      end
+
+      def test_doesnt_merge_nil_values
+        assert_equal(
+          {"Some/Rule" => {"Description" => nil}},
+          @subject.merge(
+            {"Some/Rule" => {"Description" => nil}},
+            {"Some/Rule" => {"Description" => "foo"}}
+          )
+        )
+      end
+
+      def test_doesnt_override_defined_values
+        assert_equal(
+          {"Some/Rule" => {"Enabled" => false}},
+          @subject.merge(
+            {"Some/Rule" => {"Enabled" => false}},
+            {"Some/Rule" => {"Enabled" => true}}
+          )
+        )
+      end
+
+      def test_doesnt_munge_arrays
+        assert_equal(
+          {"Some/Rule" => {"Included" => ["lol"]}},
+          @subject.merge(
+            {"Some/Rule" => {"Included" => ["lol"]}},
+            {"Some/Rule" => {"Included" => ["kek"]}}
+          )
+        )
+      end
+
+      def test_doesnt_munge_hashes
+        assert_equal(
+          {"Some/Rule" => {"Conf" => {a: 1}}},
+          @subject.merge(
+            {"Some/Rule" => {"Conf" => {a: 1}}},
+            {"Some/Rule" => {"Conf" => {a: 2, b: 3}}}
+          )
+        )
+      end
+    end
+  end
+end