Raise error if infinite correction loop

spec/ameba/runner_spec.cr

@@ -8,6 +8,13 @@ module Ameba
 
     config.update_rule ErrorRule.rule_name, enabled: false
     config.update_rule PerfRule.rule_name, enabled: false
+    config.update_rule AtoAA.rule_name, enabled: false
+    config.update_rule AtoB.rule_name, enabled: false
+    config.update_rule BtoA.rule_name, enabled: false
+    config.update_rule BtoC.rule_name, enabled: false
+    config.update_rule CtoA.rule_name, enabled: false
+    config.update_rule ClassToModule.rule_name, enabled: false
+    config.update_rule ModuleToClass.rule_name, enabled: false
 
     Runner.new(config)
   end
@@ -54,6 +61,15 @@ module Ameba
         Runner.new(all_rules, [source], formatter, default_severity).run.success?.should be_true
       end
 
+      it "aborts because of an infinite loop" do
+        rules = [AtoAA.new] of Rule::Base
+        source = Source.new "class A; end", "source.cr"
+        message = "Infinite loop in source.cr caused by Ameba/AtoAA"
+        expect_raises(Runner::InfiniteCorrectionLoopError, message) do
+          Runner.new(rules, [source], formatter, default_severity, autocorrect: true).run
+        end
+      end
+
       context "exception in rule" do
         it "raises an exception raised in fiber while running a rule" do
           rule = RaiseRule.new
@@ -180,5 +196,56 @@ module Ameba
           .run.success?.should be_true
       end
     end
+
+    describe "#run with rules autocorrecting each other" do
+      context "with two conflicting rules" do
+        context "if there is an offense in an inspected file" do
+          it "aborts because of an infinite loop" do
+            rules = [AtoB.new, BtoA.new]
+            source = Source.new "class A; end", "source.cr"
+            message = "Infinite loop in source.cr caused by Ameba/AtoB -> Ameba/BtoA"
+            expect_raises(Runner::InfiniteCorrectionLoopError, message) do
+              Runner.new(rules, [source], formatter, default_severity, autocorrect: true).run
+            end
+          end
+        end
+
+        context "if there are multiple offenses in an inspected file" do
+          it "aborts because of an infinite loop" do
+            rules = [AtoB.new, BtoA.new]
+            source = Source.new %(
+              class A; end
+              class A_A; end
+            ), "source.cr"
+            message = "Infinite loop in source.cr caused by Ameba/AtoB -> Ameba/BtoA"
+            expect_raises(Runner::InfiniteCorrectionLoopError, message) do
+              Runner.new(rules, [source], formatter, default_severity, autocorrect: true).run
+            end
+          end
+        end
+      end
+
+      context "with two pairs of conflicting rules" do
+        it "aborts because of an infinite loop" do
+          rules = [ClassToModule.new, ModuleToClass.new, AtoB.new, BtoA.new]
+          source = Source.new "class A_A; end", "source.cr"
+          message = "Infinite loop in source.cr caused by Ameba/ClassToModule, Ameba/AtoB -> Ameba/ModuleToClass, Ameba/BtoA"
+          expect_raises(Runner::InfiniteCorrectionLoopError, message) do
+            Runner.new(rules, [source], formatter, default_severity, autocorrect: true).run
+          end
+        end
+      end
+
+      context "with three rule cycle" do
+        it "aborts because of an infinite loop" do
+          rules = [AtoB.new, BtoC.new, CtoA.new]
+          source = Source.new "class A; end", "source.cr"
+          message = "Infinite loop in source.cr caused by Ameba/AtoB -> Ameba/BtoC -> Ameba/CtoA"
+          expect_raises(Runner::InfiniteCorrectionLoopError, message) do
+            Runner.new(rules, [source], formatter, default_severity, autocorrect: true).run
+          end
+        end
+      end
+    end
   end
 end

spec/spec_helper.cr

@@ -95,6 +95,133 @@ module Ameba
     end
   end
 
+  class AtoAA < Rule::Base
+    include AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ClassDef | Crystal::ModuleDef)
+      return unless (name = node_source(node.name, source.lines))
+      return unless name.includes?("A")
+
+      issue_for(node.name, message: "A to AA") do |corrector|
+        corrector.replace(node.name, name.sub("A", "AA"))
+      end
+    end
+  end
+
+  class AtoB < Rule::Base
+    include AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ClassDef | Crystal::ModuleDef)
+      return unless (name = node_source(node.name, source.lines))
+      return unless name.includes?("A")
+
+      issue_for(node.name, message: "A to B") do |corrector|
+        corrector.replace(node.name, name.tr("A", "B"))
+      end
+    end
+  end
+
+  class BtoA < Rule::Base
+    include AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ClassDef | Crystal::ModuleDef)
+      return unless (name = node_source(node.name, source.lines))
+      return unless name.includes?("B")
+
+      issue_for(node.name, message: "B to A") do |corrector|
+        corrector.replace(node.name, name.tr("B", "A"))
+      end
+    end
+  end
+
+  class BtoC < Rule::Base
+    include AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ClassDef | Crystal::ModuleDef)
+      return unless (name = node_source(node.name, source.lines))
+      return unless name.includes?("B")
+
+      issue_for(node.name, message: "B to C") do |corrector|
+        corrector.replace(node.name, name.tr("B", "C"))
+      end
+    end
+  end
+
+  class CtoA < Rule::Base
+    include AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ClassDef | Crystal::ModuleDef)
+      return unless (name = node_source(node.name, source.lines))
+      return unless name.includes?("C")
+
+      issue_for(node.name, message: "C to A") do |corrector|
+        corrector.replace(node.name, name.tr("C", "A"))
+      end
+    end
+  end
+
+  class ClassToModule < Ameba::Rule::Base
+    include Ameba::AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ClassDef)
+      return unless (location = node.location)
+
+      end_location = Crystal::Location.new(
+        location.filename,
+        location.line_number,
+        location.column_number + "class".size - 1
+      )
+      issue_for(location, end_location, message: "class to module") do |corrector|
+        corrector.replace(location, end_location, "module")
+      end
+    end
+  end
+
+  class ModuleToClass < Ameba::Rule::Base
+    include Ameba::AST::Util
+
+    properties do
+      description "This rule is only used to test infinite loop detection"
+    end
+
+    def test(source, node : Crystal::ModuleDef)
+      return unless (location = node.location)
+
+      end_location = Crystal::Location.new(
+        location.filename,
+        location.line_number,
+        location.column_number + "module".size - 1
+      )
+      issue_for(location, end_location, message: "module to class") do |corrector|
+        corrector.replace(location, end_location, "class")
+      end
+    end
+  end
+
   class DummyFormatter < Formatter::BaseFormatter
     property started_sources : Array(Source)?
     property finished_sources : Array(Source)?