Feature broken return

docs/inspections.md

@@ -28,6 +28,7 @@ The power of Mulang is grounded on more than 120 different kind of inspections
 | `DoesTypeTest`                    |
 | `HasAssignmentCondition`          | is the code evaluating the result of an assignment where a boolean condition is expected?
 | `HasAssignmentReturn`             | is the code returning the result of an assignment?
+| `HasBrokenReturn`                 | does the given function return a value only in some but not all scenarios
 | `HasCodeDuplication`              | has the given code simple literal code duplication?
 | `HasDeclarationTypos`             | is an identifier *not* declared but a very similar one declared instead?
 | `HasEmptyIfBranches`              | has the given code an empty `if` branch?

spec/JavaScriptSpec.hs

@@ -38,6 +38,9 @@ spec = do
     it "differentiates procedures and functions" $ do
       (js "function f() { return 1 }" /= js "function f() { 1 }") `shouldBe` True
 
+    it "differentiates procedures and functions with returns in if" $ do
+      (js "function f(){ if (x) { } else { return 4 } }") `shouldBe` (SimpleFunction "f" [] (If (Reference "x") None (Return (MuNumber 4.0))))
+
     it "handles lambdas likes haskell does" $ do
       js "var m = function(x) { return 1 }" `shouldBe` hs "m = \\x -> 1"
 

spec/SmellSpec.hs

@@ -128,6 +128,40 @@ spec = do
     it "is False when local variable is used as a cache" $ do
       hasRedundantLocalVariableReturn (js "function x(m) { var x = 5; var y = 1 + x; g(y); return x; }") `shouldBe` False
 
+  describe "hasBrokenReturn" $ do
+    it "is False when there are no functions" $ do
+      hasBrokenReturn (js "let y = 0; if (x) { y = 0 } ") `shouldBe` False
+
+    it "is False when there is a function that has only a return" $ do
+      hasBrokenReturn (js "function f(){ return 4 } ") `shouldBe` False
+
+    it "is False when there is a function that has a single flow and return" $ do
+      hasBrokenReturn (js "function f(){ console.log(2); return 4 } ") `shouldBe` False
+
+    it "is False when there is a function that has an if with no returns " $ do
+      hasBrokenReturn (js "function f(){ if (x) { console.log(4) } else { console.log(5) } return 4 } ") `shouldBe` False
+
+    it "is False when there is a function that has an if with no returns and no else " $ do
+        hasBrokenReturn (js "function f(){ if (x) { console.log(4) } return 4 } ") `shouldBe` False
+
+    it "is True when there is a function that has an if with a return and no else and not trailing return " $ do
+        hasBrokenReturn (js "function f(){ if (x) { return 4 } } ") `shouldBe` True
+
+    it "is True when there is a function that has an if with a return in else but not then and not trailing return " $ do
+        hasBrokenReturn (js "function f(){ if (x) { } else { return 4 } }") `shouldBe` True
+
+    it "is True when there is a function that nested ifs with incomplete return and no trailing return " $ do
+        hasBrokenReturn (js "function f(){ if (x) { if (y) { return 5 } } else { return 4 } }") `shouldBe` True
+
+    it "is False when there is a function that has an if with a return and no else and trailing return " $ do
+        hasBrokenReturn (js "function f(){ if (x) { return 4 } return 5; } ") `shouldBe` False
+
+    it "is False when there is a function that has an if with a return in else but not then and trailing return " $ do
+        hasBrokenReturn (js "function f(){ if (x) { } else { return 4 } return 5; } ") `shouldBe` False
+
+    it "is False when there is a function that nested ifs with complete return and no trailing return " $ do
+        hasBrokenReturn (js "function f(){ if (x) { if (y) { return 5 } else { return 6 } } else { return 4 } }") `shouldBe` False
+
 
   describe "hasAssignmentCondition" $ do
     it "is True when assigns within an if condition" $ do

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

@@ -5,6 +5,7 @@ module Language.Mulang.Inspector.Generic.Smell (
   doesConsolePrint,
   doesNilTest,
   doesTypeTest,
+  hasBrokenReturn,
   hasAssignmentReturn,
   hasAssignmentCondition,
   hasEmptyIfBranches,
@@ -140,6 +141,21 @@ hasRedundantLocalVariableReturn = containsExpression f
                       Return (Reference returnedVariable)]) = returnedVariable == declaredVariable
         f _                                                 = False
 
+hasBrokenReturn :: Inspection
+hasBrokenReturn = containsDeclaration f
+  where
+    f (SimpleFunction _ _ body) = not . fullyReturns $ body
+    f _                         = False
+
+    fullyReturns :: Expression -> Bool
+    fullyReturns (Sequence (Return _:_))    = True
+    fullyReturns (Sequence (If _ b1 b2:es)) = fullyReturns b1 && fullyReturns b2 || fullyReturns (Sequence es)
+    fullyReturns (Sequence (_:es))          = fullyReturns (Sequence es)
+    fullyReturns (Return _)                 = True
+    fullyReturns (If _ b1 b2)               = fullyReturns b1 && fullyReturns b2
+    fullyReturns _                          = False
+
+
 hasAssignmentCondition :: Inspection
 hasAssignmentCondition = containsExpression f
   where f (If (Unification _ _) _ _)  = True

src/Language/Mulang/Parsers/JavaScript.hs

@@ -121,7 +121,9 @@ computationFor body | containsReturn body = Function
                     | otherwise           = Procedure
 
 containsReturn :: Expression -> Bool
+containsReturn (Return None) = False
 containsReturn (Return _)    = True
+containsReturn (If _ t e)    = containsReturn t || containsReturn e
 containsReturn (Sequence xs) = any containsReturn xs
 containsReturn _             = False