Organize the NoUnusedVariable rule tests

tests/NoUnusedVariablesTest.elm

@@ -10,8 +10,25 @@ testRule =
     Lint.Test.run rule
 
 
-tests : List Test
-tests =
+all : Test
+all =
+    describe "NoUnusedVariables"
+        [ describe "Top-level variables" topLevelVariablesTests
+        , describe "let..in" letInTests
+        , describe "Top-level variables used inside a let..in" topLevelVariablesUsedInLetInTests
+        , describe "Record updates" recordUpdateTests
+        , describe "Function parameters" functionParameterTests
+        , describe "Imports" importTests
+        , describe "Pattern matching variables" patternMatchingVariablesTests
+        , describe "Defined types" typeTests
+        , describe "Opaque Types" opaqueTypeTests
+        , describe "Operators" operatorTests
+        , describe "Ports" portTests
+        ]
+
+
+topLevelVariablesTests : List Test
+topLevelVariablesTests =
     [ test "should not report exposed top-level variables" <|
         \() ->
             testRule """module A exposing (a)
@@ -93,7 +110,24 @@ c = 3"""
                         , under = "c"
                         }
                     ]
-    , test "should report unused variables from let declarations" <|
+    , test "should report unused variable even if a homonym from a module is used" <|
+        \() ->
+            testRule """module A exposing (a)
+href = 1
+a = Html.Styled.Attributes.href"""
+                |> Lint.Test.expectErrors
+                    [ Lint.Test.error
+                        { message = "Variable `href` is not used"
+                        , under = "href"
+                        }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 1 }, end = { row = 2, column = 5 } }
+                    ]
+    ]
+
+
+letInTests : List Test
+letInTests =
+    [ test "should report unused variables from let declarations" <|
         \() ->
             testRule """module A exposing (a)
 a = let b = 1
@@ -118,7 +152,7 @@ a = let b = 1
                     ]
     , test "should report unused functions from let even if they are exposed by name" <|
         \() ->
-            testRule """module A exposing (a)
+            testRule """module A exposing (a, b)
 a = let b param = 1
     in 2"""
                 |> Lint.Test.expectErrors
@@ -126,6 +160,7 @@ a = let b param = 1
                         { message = "Variable `b` is not used"
                         , under = "b"
                         }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 9 }, end = { row = 2, column = 10 } }
                     ]
     , test "should report unused variables from let even if everything is exposed" <|
         \() ->
@@ -138,34 +173,50 @@ a = let b = 1
                         , under = "b"
                         }
                     ]
-    , test "should not report top-level variables used inside a let expression" <|
+    , test "should not report variables from let declarations that are used in the expression" <|
+        \() ->
+            testRule """module A exposing (a)
+a = let c = 1
+    in c"""
+                |> Lint.Test.expectNoErrors
+    ]
+
+
+topLevelVariablesUsedInLetInTests : List Test
+topLevelVariablesUsedInLetInTests =
+    [ test "should not report top-level variables used inside a let expression" <|
         \() ->
             testRule """module A exposing (a)
 b = 1
 a = let c = 1
-    in b + c"""
+in b + c"""
                 |> Lint.Test.expectNoErrors
     , test "should not report top-level variables used inside let declarations" <|
         \() ->
             testRule """module A exposing (a)
 b = 1
 a = let c = b
-    in c"""
+in c"""
                 |> Lint.Test.expectNoErrors
     , test "should not report top-level variables used in nested lets" <|
         \() ->
             testRule """module A exposing (a)
 b = 1
 a = let
-      c = b
-      d = let
-            e = 1
-          in
-            b + c + e
-    in
-      d"""
+  c = b
+  d = let
+        e = 1
+      in
+        b + c + e
+in
+  d"""
                 |> Lint.Test.expectNoErrors
-    , test "should not report variables used in a record update expression's value to be updated" <|
+    ]
+
+
+recordUpdateTests : List Test
+recordUpdateTests =
+    [ test "should not report variables used in a record update expression's value to be updated" <|
         \() ->
             testRule """module A exposing (a)
 b = { c = 1 }
@@ -192,18 +243,22 @@ a = { b | c = 3 }"""
                         }
                         |> Lint.Test.atExactly { start = { row = 3, column = 1 }, end = { row = 3, column = 2 } }
                     ]
-    , test "should not report variables from let declarations that are used in the expression" <|
-        \() ->
-            testRule """module A exposing (a)
-a = let c = 1
-    in c"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report unused function parameters" <|
+    ]
+
+
+functionParameterTests : List Test
+functionParameterTests =
+    [ test "should not report unused function parameters" <|
         \() ->
             testRule """module A exposing (a)
 a n = 1"""
                 |> Lint.Test.expectNoErrors
-    , test "should report unused imported functions" <|
+    ]
+
+
+importTests : List Test
+importTests =
+    [ test "should report unused imported functions" <|
         \() ->
             testRule """module A exposing (b)
 import Foo exposing (a)"""
@@ -231,165 +286,6 @@ import Foo exposing (C, a, b)"""
                         , under = "b"
                         }
                     ]
-    , test "should not report unused pattern matching parameters" <|
-        \() ->
-            testRule """module A exposing (a)
-a = case thing of
-    Foo b c -> []"""
-                |> Lint.Test.expectNoErrors
-
-    -- Should B and C be reported if they are not used? Probably.
-    , test "should report unused custom type declarations" <|
-        \() ->
-            testRule """module A exposing (a)
-type A = B | C"""
-                |> Lint.Test.expectErrors
-                    [ Lint.Test.error
-                        { message = "Type `A` is not used"
-                        , under = "A"
-                        }
-                        |> Lint.Test.atExactly { start = { row = 2, column = 6 }, end = { row = 2, column = 7 } }
-                    ]
-    , test "should report unused type aliases declarations" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }"""
-                |> Lint.Test.expectErrors
-                    [ Lint.Test.error
-                        { message = "Type `A` is not used"
-                        , under = "A"
-                        }
-                        |> Lint.Test.atExactly { start = { row = 2, column = 12 }, end = { row = 2, column = 13 } }
-                    ]
-    , test "should not report type used in a signature" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }
-a : A
-a = {a = 1}"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a signature with multiple arguments" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }
-a : String -> A
-a str = {a = str}"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a signature with parameterized types (as generic type)" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }
-a : A B
-a = []"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a signature with parameterized types (as parameter)" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }
-a : List A
-a = []"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a signature with a record" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }
-a : { c: A }
-a str = {c = str}"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a signature with a generic record" <|
-        \() ->
-            testRule """module A exposing (a)
-type alias A = { a : B }
-a : { r | c: A }
-a str = {c = str}"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a custom type constructor definition" <|
-        \() ->
-            testRule """module A exposing (ExposedType)
-type A = B
-
-type ExposedType = Something A
-"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report a type of which a constructor is used" <|
-        \() ->
-            testRule """module A exposing (b)
-type A = B | C | D
-
-b = B
-"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report a type of which a constructor is used even if it was defined afterwards" <|
-        \() ->
-            testRule """module A exposing (b)
-b = B
-
-type A = B | C | D
-"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in type signature inside a let-in" <|
-        \() ->
-            testRule """module A exposing (a)
-type A = A
-
-a = let
-      b : A
-      b = 1
-    in
-    b
-"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a type alias field" <|
-        \() ->
-            testRule """module A exposing (ExposedType)
-type A = B | C
-
-type alias ExposedType = { a : A }
-"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type used in a type alias field's arguments " <|
-        \() ->
-            testRule """module A exposing (ExposedType)
-type A = B | C
-
-type alias ExposedType = { a : Maybe A }
-"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report type if it's exposed" <|
-        \() ->
-            testRule """module A exposing (A)
-type A a = B a"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report custom type if it's exposed with its sub-types" <|
-        \() ->
-            testRule """module A exposing (A(..))
-type A = B | C | D"""
-                |> Lint.Test.expectNoErrors
-    , test "should report unused variable even if it's present in a generic type" <|
-        \() ->
-            testRule """module A exposing (A)
-a = 1
-type A a = B a"""
-                |> Lint.Test.expectErrors
-                    [ Lint.Test.error
-                        { message = "Variable `a` is not used"
-                        , under = "a"
-                        }
-                        |> Lint.Test.atExactly { start = { row = 2, column = 1 }, end = { row = 2, column = 2 } }
-                    ]
-    , test "should report unused variable even if it's present in a generic record type" <|
-        \() ->
-            testRule """module A exposing (a)
-r = 1
-a : { r | c: A }
-a str = {c = str}"""
-                |> Lint.Test.expectErrors
-                    [ Lint.Test.error
-                        { message = "Variable `r` is not used"
-                        , under = "r"
-                        }
-                        |> Lint.Test.atExactly { start = { row = 2, column = 1 }, end = { row = 2, column = 2 } }
-                    ]
     , test "should report unused operator import" <|
         \() ->
             testRule """module A exposing (a)
@@ -400,36 +296,6 @@ import Parser exposing ((</>))"""
                         , under = "(</>)"
                         }
                     ]
-    , test "should not report used operator (infix)" <|
-        \() ->
-            testRule """module A exposing (a)
-import Parser exposing ((</>))
-a = 1 </> 2"""
-                |> Lint.Test.expectNoErrors
-    , test "should not report used operator (prefix)" <|
-        \() ->
-            testRule """module A exposing (a)
-import Parser exposing ((</>))
-a = (</>) 2"""
-                |> Lint.Test.expectNoErrors
-    , test "should report unused opaque types" <|
-        \() ->
-            testRule """module A exposing (a)
-type A = A Int"""
-                |> Lint.Test.expectErrors
-                    [ Lint.Test.error
-                        { message = "Type `A` is not used"
-                        , under = "A"
-                        }
-                        |> Lint.Test.atExactly { start = { row = 2, column = 6 }, end = { row = 2, column = 7 } }
-                    ]
-    , test "should not report used opaque types" <|
-        \() ->
-            testRule """module A exposing (a)
-type A = A Int
-a : A
-a = 1"""
-                |> Lint.Test.expectNoErrors
     , test "should report unused import" <|
         \() ->
             testRule """module A exposing (a)
@@ -455,18 +321,6 @@ import Html.Styled.Attributes"""
             testRule """module A exposing (a)
 import Html.Styled.Attributes exposing (..)"""
                 |> Lint.Test.expectNoErrors
-    , test "should report unused variable even if a homonym from a module is used" <|
-        \() ->
-            testRule """module A exposing (a)
-href = 1
-a = Html.Styled.Attributes.href"""
-                |> Lint.Test.expectErrors
-                    [ Lint.Test.error
-                        { message = "Variable `href` is not used"
-                        , under = "href"
-                        }
-                        |> Lint.Test.atExactly { start = { row = 2, column = 1 }, end = { row = 2, column = 5 } }
-                    ]
     , test "should not report used import (function access)" <|
         \() ->
             testRule """module A exposing (a)
@@ -504,7 +358,291 @@ import B exposing (C(..))
 a : D
 a = 1"""
                 |> Lint.Test.expectNoErrors
-    , test "should not report types that are used in ports" <|
+    ]
+
+
+patternMatchingVariablesTests : List Test
+patternMatchingVariablesTests =
+    [ test "should not report unused pattern matching parameters" <|
+        \() ->
+            testRule """module A exposing (a)
+a = case thing of
+    Foo b c -> []"""
+                |> Lint.Test.expectNoErrors
+    ]
+
+
+typeTests : List Test
+typeTests =
+    [ test "should report unused custom type declarations" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = B | C"""
+                |> Lint.Test.expectErrors
+                    [ Lint.Test.error
+                        { message = "Type `A` is not used"
+                        , under = "A"
+                        }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 6 }, end = { row = 2, column = 7 } }
+                    ]
+    , test "should not report unused custom type constructors" <|
+        -- This is handled by the `NoUnusedTypeConstructors` rule
+        \() ->
+            testRule """module A exposing (A)
+type A = B | C"""
+                |> Lint.Test.expectNoErrors
+    , test "should report unused type aliases declarations" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }"""
+                |> Lint.Test.expectErrors
+                    [ Lint.Test.error
+                        { message = "Type `A` is not used"
+                        , under = "A"
+                        }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 12 }, end = { row = 2, column = 13 } }
+                    ]
+    , test "should not report type alias used in a signature" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }
+a : A
+a = {a = 1}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a signature with multiple arguments" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }
+a : String -> A
+a str = {a = str}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a signature" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = B | C
+a : A
+a = {a = 1}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a signature with multiple arguments" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = B | C
+a : String -> A
+a str = {a = str}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report parameterized custom type used in a signature" <|
+        \() ->
+            testRule """module A exposing (a)
+type CustomMaybe a = B a | C a
+a : CustomMaybe D
+a = []"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a signature with parameterized types (as parameter)" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }
+a : List A
+a = []"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a signature with parameterized types (as parameter)" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = B | C
+a : List A
+a = []"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a signature with a record" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }
+a : { c: A }
+a str = {c = str}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a signature with a record" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = B | C
+a : { c: A }
+a str = {c = str}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a signature with a generic record" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }
+a : { r | c: A }
+a str = {c = str}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a signature with a generic record" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = B | C
+a : { r | c: A }
+a str = {c = str}"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a custom type constructor definition" <|
+        \() ->
+            testRule """module A exposing (ExposedType)
+type alias A = { a : B }
+type ExposedType = Something A
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a custom type constructor definition" <|
+        \() ->
+            testRule """module A exposing (ExposedType)
+type A = B
+type ExposedType = Something A
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type of which a constructor is used" <|
+        \() ->
+            testRule """module A exposing (b)
+type A = B | C | D
+b = B
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type of which a constructor is used even if it was defined afterwards" <|
+        \() ->
+            testRule """module A exposing (b)
+b = B
+type A = B | C | D
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in type signature inside a let..in" <|
+        \() ->
+            testRule """module A exposing (a)
+type alias A = { a : B }
+a = let
+      b : A
+      b = 1
+    in
+    b
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in type signature inside a let..in" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = A
+a = let
+      b : A
+      b = 1
+    in
+    b
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a type alias field" <|
+        \() ->
+            testRule """module A exposing (ExposedType)
+type alias A = { a : B }
+type alias ExposedType = { a : A }
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a type alias field" <|
+        \() ->
+            testRule """module A exposing (ExposedType)
+type A = B | C
+type alias ExposedType = { a : A }
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias used in a type alias field's arguments " <|
+        \() ->
+            testRule """module A exposing (ExposedType)
+type alias A = { a : B }
+type alias ExposedType = { a : Maybe A }
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type used in a type alias field's arguments " <|
+        \() ->
+            testRule """module A exposing (ExposedType)
+type A = B | C
+type alias ExposedType = { a : Maybe A }
+"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report type alias if it's exposed" <|
+        \() ->
+            testRule """module A exposing (A)
+type alias A = { a : B }"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type if it's exposed" <|
+        \() ->
+            testRule """module A exposing (A)
+type A a = B a"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report custom type if it's exposed with its sub-types" <|
+        \() ->
+            testRule """module A exposing (A(..))
+type A = B | C | D"""
+                |> Lint.Test.expectNoErrors
+    , test "should report unused variable even if it's named like a custom type parameter" <|
+        \() ->
+            testRule """module A exposing (A)
+a = 1
+type A a = B a"""
+                |> Lint.Test.expectErrors
+                    [ Lint.Test.error
+                        { message = "Variable `a` is not used"
+                        , under = "a"
+                        }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 1 }, end = { row = 2, column = 2 } }
+                    ]
+    , test "should report unused variable even if it's present in a generic record type" <|
+        \() ->
+            testRule """module A exposing (a)
+r = 1
+a : { r | c: A }
+a str = {c = str}"""
+                |> Lint.Test.expectErrors
+                    [ Lint.Test.error
+                        { message = "Variable `r` is not used"
+                        , under = "r"
+                        }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 1 }, end = { row = 2, column = 2 } }
+                    ]
+    ]
+
+
+opaqueTypeTests : List Test
+opaqueTypeTests =
+    [ test "should report unused opaque types" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = A Int"""
+                |> Lint.Test.expectErrors
+                    [ Lint.Test.error
+                        { message = "Type `A` is not used"
+                        , under = "A"
+                        }
+                        |> Lint.Test.atExactly { start = { row = 2, column = 6 }, end = { row = 2, column = 7 } }
+                    ]
+    , test "should not report used opaque types" <|
+        \() ->
+            testRule """module A exposing (a)
+type A = A Int
+a : A
+a = 1"""
+                |> Lint.Test.expectNoErrors
+    ]
+
+
+operatorTests : List Test
+operatorTests =
+    [ test "should not report used operator (infix)" <|
+        \() ->
+            testRule """module A exposing (a)
+import Parser exposing ((</>))
+a = 1 </> 2"""
+                |> Lint.Test.expectNoErrors
+    , test "should not report used operator (prefix)" <|
+        \() ->
+            testRule """module A exposing (a)
+import Parser exposing ((</>))
+a = (</>) 2"""
+                |> Lint.Test.expectNoErrors
+    ]
+
+
+portTests : List Test
+portTests =
+    [ test "should not report types that are used in ports" <|
         \() ->
             testRule """module A exposing (output, input)
 import Json.Decode
@@ -535,8 +673,3 @@ port output : Json.Encode.Value -> Cmd msg"""
                         }
                     ]
     ]
-
-
-all : Test
-all =
-    describe "NoUnusedVariables" tests