New rule: SharedVarInSpawn

closes #132

spec/ameba/rule/lint/shared_var_in_fiber_spec.cr

@@ -0,0 +1,236 @@
+require "../../../spec_helper"
+
+module Ameba::Rule::Lint
+  describe SharedVarInFiber do
+    subject = SharedVarInFiber.new
+
+    it "doesn't report if there is only local shared var in fiber" do
+      s = Source.new %(
+        spawn do
+          i = 1
+          puts i
+        end
+
+        Fiber.yield
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if there is only block shared var in fiber" do
+      s = Source.new %(
+        10.times do |i|
+          spawn do
+            puts i
+          end
+        end
+
+        Fiber.yield
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if there a spawn macro is used" do
+      s = Source.new %(
+        i = 0
+        while i < 10
+          spawn puts(i)
+          i += 1
+        end
+
+        Fiber.yield
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "reports if there is a shared var in spawn" do
+      s = Source.new %(
+        i = 0
+        while i < 10
+          spawn do
+            puts(i)
+          end
+          i += 1
+        end
+
+        Fiber.yield
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports reassigned reference to shared var in spawn" do
+      s = Source.new %(
+        channel = Channel(String).new
+        n = 0
+
+        while n < 10
+          n = n + 1
+          spawn do
+            m = n
+            channel.send m
+          end
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "doesn't report reassigned reference to shared var in block" do
+      s = Source.new %(
+        channel = Channel(String).new
+        n = 0
+
+        while n < 3
+          n = n + 1
+          m = n
+          spawn do
+            channel.send m
+          end
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "does not report block is called in a spawn" do
+      s = Source.new %(
+        def method(block)
+          spawn do
+            block.call(10)
+          end
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "reports multiple shared variables in spawn" do
+      s = Source.new %(
+        foo, bar, baz = 0, 0, 0
+        while foo < 10
+          baz += 1
+          spawn do
+            puts foo
+            puts foo + bar + baz
+          end
+          foo += 1
+        end
+      )
+      subject.catch(s).should_not be_valid
+      s.issues.size.should eq 3
+      s.issues[0].location.to_s.should eq ":5:10"
+      s.issues[0].end_location.to_s.should eq ":5:12"
+      s.issues[0].message.should eq "Shared variable `foo` is used in fiber"
+
+      s.issues[1].location.to_s.should eq ":6:10"
+      s.issues[1].end_location.to_s.should eq ":6:12"
+      s.issues[1].message.should eq "Shared variable `foo` is used in fiber"
+
+      s.issues[2].location.to_s.should eq ":6:22"
+      s.issues[2].end_location.to_s.should eq ":6:24"
+      s.issues[2].message.should eq "Shared variable `baz` is used in fiber"
+    end
+
+    it "doesn't report if variable is passed to the proc" do
+      s = Source.new %(
+        i = 0
+        while i < 10
+          proc = ->(x : Int32) do
+            spawn do
+            puts(x)
+            end
+          end
+          proc.call(i)
+          i += 1
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if a channel is declared in outer scope" do
+      s = Source.new %(
+        channel = Channel(Nil).new
+        spawn { channel.send(nil) }
+        channel.receive
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if there is a loop in spawn" do
+      s = Source.new %(
+        channel = Channel(String).new
+
+        spawn do
+          server = TCPServer.new("0.0.0.0", 8080)
+          socket = server.accept
+          while line = socket.gets
+            channel.send(line)
+          end
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if a var is mutated in spawn and referenced outside" do
+      s = Source.new %(
+        def method
+          foo = 1
+          spawn { foo = 2 }
+          foo
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if variable is changed without iterations" do
+      s = Source.new %(
+        def foo
+          i = 0
+          i += 1
+          spawn { i }
+        end
+      ), "source.cr"
+
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if variable is in a loop inside spawn" do
+      s = Source.new %(
+        i = 0
+        spawn do
+          while i < 10
+            i += 1
+          end
+        end
+      )
+
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if variable declared inside loop" do
+      s = Source.new %(
+        while true
+          i = 0
+          spawn { i += 1 }
+        end
+      )
+
+      subject.catch(s).should be_valid
+    end
+
+    it "reports rule, location and message" do
+      s = Source.new %(
+        i = 0
+        while true
+          i += 1
+          spawn { i }
+        end
+      ), "source.cr"
+
+      subject.catch(s).should_not be_valid
+      s.issues.size.should eq 1
+
+      issue = s.issues.first
+      issue.rule.should_not be_nil
+      issue.location.to_s.should eq "source.cr:4:11"
+      issue.end_location.to_s.should eq "source.cr:4:11"
+      issue.message.should eq "Shared variable `i` is used in fiber"
+    end
+  end
+end

spec/ameba/rule/lint/useless_assign_spec.cr

@@ -921,23 +921,6 @@ module Ameba::Rule::Lint
         subject.catch(s).should be_valid
       end
 
-      it "reports if assignment is referenced in macro def in a different scope" do
-        s = Source.new %(
-          class Foo
-            def foo
-              x = 1
-            end
-          end
-
-          class Bar
-            macro macro_call
-              puts x
-            end
-          end
-        )
-        subject.catch(s).should_not be_valid
-      end
-
       it "doesn't report if assignment is referenced in a macro below" do
         s = Source.new %(
           class Foo