         XCTAssertEqual(disabledConfig.disabledRules,
                        ["nesting", "todo"],
                        "initializing Configuration with valid rules in Dictionary should succeed")
-        let expectedIdentifiers = Set(masterRuleList.list.keys
+        let expectedIdentifiers = Array(masterRuleList.list.keys
             .filter({ !(["nesting", "todo"] + optInRules).contains($0) }))
-        let configuredIdentifiers = Set(disabledConfig.rules.map {
-            type(of: $0).description.identifier
-        })
+        let configuredIdentifiers = disabledConfig.rules.map {
+            type(of: $0).description.identifier
+        }
         XCTAssertEqual(expectedIdentifiers, configuredIdentifiers)
 
         // Duplicate

        let ruleConfiguration = [1, 2]
        let config = [RuleWithLevelsMock.description.identifier: ruleConfiguration]
        let rules = try testRuleList.configuredRules(with: config)
        XCTAssertTrue(rules == [try RuleWithLevelsMock(configuration: ruleConfiguration) as Rule])
    }

    func testConfigureFallsBackCorrectly() throws {
        let config = [RuleWithLevelsMock.description.identifier: ["a", "b"]]
        let rules = try testRuleList.configuredRules(with: config)
        XCTAssertTrue(rules == [RuleWithLevelsMock() as Rule])
    }

    // MARK: - Aliases

        let ruleConfiguration = [1, 2]
        let config = ["severity_mock": ruleConfiguration]
        let rules = try testRuleList.configuredRules(with: config)
        XCTAssertTrue(rules == [try RuleWithLevelsMock(configuration: ruleConfiguration)])
    }

    func testConfiguresCorrectlyFromDeprecatedAlias() throws {
        let ruleConfiguration = [1, 2]
        let config = ["mock": ruleConfiguration]
        let rules = try testRuleList.configuredRules(with: config)
        XCTAssertTrue(rules == [try RuleWithLevelsMock(configuration: ruleConfiguration)])
    }

    func testReturnsNilWithDuplicatedConfiguration() {
