Decouple patterns and exclude-patterns

common/lib/dependabot/dependency_group.rb

@@ -15,6 +15,7 @@ def initialize(name:, rules:)
 
     def contains?(dependency)
       return true if @dependencies.include?(dependency)
+      return false if matches_excluded_pattern?(dependency.name)
 
       matches_pattern?(dependency.name) && matches_dependency_type?(dependency)
     end
@@ -33,30 +34,25 @@ def to_config_yaml
     private
 
     def matches_pattern?(dependency_name)
-      return true unless pattern_rules? # If no patterns are defined, we pass this check by default
+      return true unless rules.key?("patterns") # If no patterns are defined, we pass this check by default
 
-      positive_match = rules["patterns"].any? { |rule| WildcardMatcher.match?(rule, dependency_name) }
-      negative_match = rules["exclude-patterns"]&.any? { |rule| WildcardMatcher.match?(rule, dependency_name) }
+      rules["patterns"].any? { |rule| WildcardMatcher.match?(rule, dependency_name) }
+    end
+
+    def matches_excluded_pattern?(dependency_name)
+      return false unless rules.key?("exclude-patterns") # If there are no exclusions, fail by default
 
-      positive_match && !negative_match
+      rules["exclude-patterns"].any? { |rule| WildcardMatcher.match?(rule, dependency_name) }
     end
 
     def matches_dependency_type?(dependency)
-      return true unless dependency_type_rules? # If no dependency-type is set, match by default
+      return true unless rules.key?("dependency-type") # If no dependency-type is set, match by default
 
       rules["dependency-type"] == if dependency.production?
                                     "production"
                                   else
                                     "development"
                                   end
     end
-
-    def pattern_rules?
-      rules.key?("patterns") && rules["patterns"]&.any?
-    end
-
-    def dependency_type_rules?
-      rules.key?("dependency-type")
-    end
   end
 end

common/spec/dependabot/dependency_group_spec.rb

@@ -167,9 +167,22 @@
         expect(dependency_group.contains?(test_dependency1)).to be_falsey
         expect(dependency_group.contains?(test_dependency2)).to be_falsey
       end
+
+      context "when a dependency is specifically excluded" do
+        let(:rules) do
+          {
+            "dependency-type" => "production",
+            "exclude-patterns" => [production_dependency.name]
+          }
+        end
+
+        it "returns false even if the dependency matches the specified type" do
+          expect(dependency_group.contains?(production_dependency)).to be_falsey
+        end
+      end
     end
 
-    context "when the rules specify a mix of dependency-types" do
+    context "when the rules specify a mix of conditions" do
       let(:rules) do
         {
           "patterns" => ["*dependency*"],