Shadowed argument

spec/ameba/ast/scope_spec.cr

@@ -43,14 +43,14 @@ module Ameba::AST
     it "creates a new assignment" do
       scope = Scope.new as_node("foo = 1")
       scope.add_variable Crystal::Var.new "foo"
-      scope.assign_variable(Crystal::Var.new "foo")
+      scope.assign_variable("foo", Crystal::Var.new "foo")
       scope.find_variable("foo").not_nil!.assignments.size.should eq 1
     end
 
     it "does not create the assignment if variable is wrong" do
       scope = Scope.new as_node("foo = 1")
       scope.add_variable Crystal::Var.new "foo"
-      scope.assign_variable(Crystal::Var.new "bar")
+      scope.assign_variable("bar", Crystal::Var.new "bar")
       scope.find_variable("foo").not_nil!.assignments.size.should eq 0
     end
   end

spec/ameba/rule/shadowed_argument_spec.cr

@@ -0,0 +1,165 @@
+require "../../spec_helper"
+
+module Ameba::Rule
+  describe ShadowedArgument do
+    subject = ShadowedArgument.new
+
+    it "doesn't report if there is not a shadowed argument" do
+      s = Source.new %(
+        def foo(bar)
+          baz = 1
+        end
+
+        3.times do |i|
+          a = 1
+        end
+
+        proc = -> (a : Int32) {
+          b = 2
+        }
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "reports if there is a shadowed method argument" do
+      s = Source.new %(
+        def foo(bar)
+          bar = 1
+          bar
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports if there is a shadowed block argument" do
+      s = Source.new %(
+        3.times do |i|
+          i = 2
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports if there is a shadowed proc argument" do
+      s = Source.new %(
+        ->(x : Int32) {
+          x = 20
+          x
+        }
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "doesn't report if the argument is referenced before the assignment" do
+      s = Source.new %(
+        def foo(bar)
+          bar
+          bar = 1
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if the argument is conditionally reassigned" do
+      s = Source.new %(
+        def foo(bar = nil)
+          bar ||= true
+          bar
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "doesn't report if the op assign is followed by another assignment" do
+      s = Source.new %(
+        def foo(bar)
+          bar ||= 3
+          bar = 43
+          bar
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "reports if the shadowing assignment is followed by op assign" do
+      s = Source.new %(
+        def foo(bar)
+          bar = 42
+          bar ||= 43
+          bar
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "doesn't report if the argument is unused" do
+      s = Source.new %(
+        def foo(bar)
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "reports if the argument is shadowed before super" do
+      s = Source.new %(
+        def foo(bar)
+          bar = 1
+          super
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    context "branch" do
+      it "doesn't report if the argument is not shadowed in a condition" do
+        s = Source.new %(
+          def foo(bar, baz)
+            bar = 1 if baz
+            bar
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+
+      it "reports if the argument is shadowed after the condition" do
+        s = Source.new %(
+          def foo(foo)
+            if something
+              foo = 42
+            end
+            foo = 43
+            foo
+          end
+        )
+        subject.catch(s).should_not be_valid
+      end
+
+      it "doesn't report if the argument is conditionally assigned in a branch" do
+        s = Source.new %(
+          def foo(bar)
+            if something
+              bar ||= 22
+            end
+            bar
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    it "reports rule, location and message" do
+      s = Source.new %(
+        def foo(bar)
+          bar = 22
+          bar
+        end
+      ), "source.cr"
+      subject.catch(s).should_not be_valid
+
+      error = s.errors.first
+      error.rule.should_not be_nil
+      error.location.to_s.should eq "source.cr:3:11"
+      error.message.should eq "Argument `bar` is assigned before it is used"
+    end
+  end
+end