Feature used parameter expectation

spec/SmellSpec.hs

@@ -145,6 +145,23 @@ spec = do
     it "is False when not does type test" $ do
       doesTypeTest (js "function x(m) { return 1 }") `shouldBe` False
 
+  describe "hasUnusedParameters" $ do
+    it "is False for methods of all kinds" $ do
+      hasUnusedParameters (js "var o = {x: function(m) { return 4; }}") `shouldBe` False
+      hasUnusedParameters (js "var o = {x: function(m) { return m; }}") `shouldBe` False
+
+    it "is True when has unused parameter" $ do
+      hasUnusedParameters (js "function x(m) { return 4; } ") `shouldBe` True
+
+    it "is False when uses its single parameter" $ do
+      hasUnusedParameters (js "function x(m) { return m } ") `shouldBe` False
+
+    it "is False when uses all its parameters in different places" $ do
+      hasUnusedParameters (js "function x(m2, m2) { g(m1); return m2 } ") `shouldBe` False
+
+    it "is False when uses all its parameters in return" $ do
+      hasUnusedParameters (js "function x(m2, m2) { return m1 + m2 } ") `shouldBe` False
+
   describe "hasRedundantLambda" $ do
     it "is True whn etha-conversion applies, hs" $ do
       hasRedundantLambda (hs "g = map (\\m -> f m)") `shouldBe` True

src/Language/Mulang/Inspector/Generic/Smell.hs

@@ -7,6 +7,7 @@ module Language.Mulang.Inspector.Generic.Smell (
   doesTypeTest,
   hasAssignmentReturn,
   hasEmptyIfBranches,
+  hasUnusedParameters,
   hasEmptyRepeat,
   hasLongParameterList,
   hasRedundantBooleanComparison,
@@ -26,7 +27,7 @@ module Language.Mulang.Inspector.Generic.Smell (
 
 import           Language.Mulang.Ast
 import qualified Language.Mulang.Ast.Operator as O
-import           Language.Mulang.Generator (identifierReferences)
+import           Language.Mulang.Generator (identifierReferences, expressions)
 import           Language.Mulang.Inspector.Primitive
 
 -- | Inspection that tells whether an expression has expressions like 'x == True'
@@ -172,6 +173,16 @@ shouldInvertIfCondition = containsExpression f
   where f (If _ None elseBranch) = elseBranch /= None
         f _                        = False
 
+hasUnusedParameters :: Inspection
+hasUnusedParameters = containsExpression f
+  where f (SimpleFunction _ params body) = not . all (`elem` (expressions body)) . variables $  params
+        f _                              = False
+
+        variables ps = do
+          VariablePattern v <- ps
+          return (Reference v)
+
+
 hasEmptyIfBranches :: Inspection
 hasEmptyIfBranches = containsExpression f
   where f (If _ None None) = True