DEV: Add validator for search_ranking_weights site setting (#20088)

Follow-up to 6934edd97cfdc855d5882e85415b33f573db120c

spec/lib/validators/search_ranking_weights_validator_spec.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+RSpec.describe SearchRankingWeightsValidator do
+  it 'allows a blank value to be set' do
+    expect do
+      SiteSetting.search_ranking_weights = ''
+    end.not_to raise_error
+  end
+
+  it 'raises the right error when value is invalid' do
+    expect do
+      SiteSetting.search_ranking_weights = 'test'
+    end.to raise_error(Discourse::InvalidParameters, /#{I18n.t("site_settings.errors.invalid_search_ranking_weights")}/)
+
+    expect do
+      SiteSetting.search_ranking_weights = '{1.1,0.1,0.2,0.3}'
+    end.to raise_error(Discourse::InvalidParameters, /#{I18n.t("site_settings.errors.invalid_search_ranking_weights")}/)
+  end
+
+  it 'sets the site setting when value is valid' do
+    expect do
+      SiteSetting.search_ranking_weights = '{0.001,0.2,0.003,1.0}'
+    end.to_not raise_error
+  end
+end