Enable some rubocop rules

.rubocop.yml

@@ -61,27 +61,18 @@ Metrics/MethodLength:
 Metrics/ModuleLength:
   Enabled: false
 
-Minitest/AssertPredicate:
-  Enabled: false
-
 Minitest/EmptyLineBeforeAssertionMethods:
   Enabled: false
 
 Minitest/MultipleAssertions:
   Enabled: false
 
-Minitest/RefutePredicate:
-  Enabled: false
-
 Style/Documentation:
   Enabled: false
 
 Style/EmptyMethod:
   EnforcedStyle: expanded
 
-Style/GuardClause:
-  Enabled: false
-
 Style/HashSyntax:
   EnforcedShorthandSyntax: never
 
@@ -112,9 +103,5 @@ Style/TrailingCommaInArrayLiteral:
 Style/TrailingCommaInHashLiteral:
   EnforcedStyleForMultiline: consistent_comma
 
-Rails/Output:
-  Exclude:
-    - db/*.rb
-
 Rails/OutputSafety:
   Enabled: false

app/models/artist.rb

@@ -48,9 +48,9 @@ def enqueue_all_urls
 
   def oldest_last_scraped_at
     scraper_urls = artist_urls.select(&:scraper_enabled?)
-    if scraper_urls.none? { |artist_url| artist_url.last_scraped_at.nil? }
-      scraper_urls.map(&:last_scraped_at).min
-    end
+    return nil if scraper_urls.any? { |artist_url| artist_url.last_scraped_at.nil? }
+
+    scraper_urls.map(&:last_scraped_at).min
   end
 
   def not_uploaded

test/logical/sites/scraper_definition_test.rb

@@ -11,7 +11,7 @@ class ScraperDefinitionTest < ActiveSupport::TestCase
       definition = Sites.from_enum("twitter")
 
       assert_empty(definition.missing_config_keys)
-      assert(definition.scraper_enabled?)
+      assert_predicate(definition, :scraper_enabled?)
     end
 
     it "returns false if the scraper is manually disabled" do

test/model/submission_file_test.rb

@@ -19,7 +19,7 @@ class SubmissionFileTest < ActiveSupport::TestCase
     it "can be omitted for testing purposes" do
       sm = create(:submission_file)
       assert_not sm.original.attached?
-      assert sm.valid?
+      assert_predicate(sm, :valid?)
     end
   end
 end