Make lintSource always return a list, not a result

example/Main.elm

@@ -49,7 +49,7 @@ config model =
 
 type alias Model =
     { sourceCode : String
-    , lintResult : Result (List String) (List LintError)
+    , lintErrors : List LintError
     , noDebugEnabled : Bool
     , noUnusedVariablesEnabled : Bool
     , noImportingEverythingEnabled : Bool
@@ -81,7 +81,7 @@ g n = n + 1
         tmpModel : Model
         tmpModel =
             { sourceCode = sourceCode
-            , lintResult = Result.Ok []
+            , lintErrors = []
             , noDebugEnabled = True
             , noUnusedVariablesEnabled = True
             , noImportingEverythingEnabled = True
@@ -91,7 +91,7 @@ g n = n + 1
             , showConfigurationAsText = False
             }
     in
-    { tmpModel | lintResult = lintSource (config tmpModel) sourceCode }
+    { tmpModel | lintErrors = lintSource (config tmpModel) { fileName = "", source = sourceCode } }
 
 
 
@@ -114,7 +114,7 @@ update action model =
         UserEditedSourceCode sourceCode ->
             { model
                 | sourceCode = sourceCode
-                , lintResult = lintSource (config model) sourceCode
+                , lintErrors = lintSource (config model) { fileName = "Source code", source = model.sourceCode }
             }
 
         UserToggledNoDebugRule ->
@@ -143,7 +143,11 @@ update action model =
 
 rerunLinting : Model -> Model
 rerunLinting model =
-    { model | lintResult = lintSource (config model) model.sourceCode }
+    { model
+        | lintErrors =
+            lintSource (config model)
+                { fileName = "Source code", source = model.sourceCode }
+    }
 
 
 
@@ -319,23 +323,17 @@ viewCheckbox onClick name checked =
 
 lintErrors : Model -> List Text
 lintErrors model =
-    case model.lintResult of
-        Err errors ->
-            errors
-                |> List.map Text.from
+    if List.isEmpty model.lintErrors then
+        [ Text.from "I found no linting errors.\nYou're all good!" ]
 
-        Ok errors ->
-            if List.isEmpty errors then
-                [ Text.from "I found no linting errors.\nYou're all good!" ]
-
-            else
-                Reporter.formatReport
-                    [ ( { name = "IN SOURCE CODE"
-                        , source = model.sourceCode
-                        }
-                      , errors
-                      )
-                    ]
+    else
+        Reporter.formatReport
+            [ ( { name = "Source code"
+                , source = model.sourceCode
+                }
+              , model.lintErrors
+              )
+            ]
 
 
 main : Program () Model Msg

src/Lint.elm

@@ -24,7 +24,7 @@ like the name of the rule that emitted it and the file name.
 
 -}
 type alias LintError =
-    { file : Maybe String
+    { file : String
     , ruleName : String
     , message : String
     , details : List String
@@ -40,26 +40,36 @@ type alias LintError =
         , Lint.Rule.NoUnusedVariables.rule
         ]
 
-    result =
+    errors : List LintError
+    errors =
         lintSource config sourceCode
 
 -}
-lintSource : List Rule -> String -> Result (List String) (List LintError)
-lintSource config source =
-    source
-        |> parseSource
-        |> Result.map
-            (\statements ->
-                config
-                    |> List.concatMap (lintSourceWithRule statements)
-                    |> List.sortWith compareErrorPositions
-            )
+lintSource : List Rule -> { fileName : String, source : String } -> List LintError
+lintSource config { fileName, source } =
+    case parseSource source of
+        Ok file ->
+            config
+                |> List.concatMap (lintSourceWithRule fileName file)
+                |> List.sortWith compareErrorPositions
+
+        Err _ ->
+            [ { file = fileName
+              , ruleName = "ParsingError"
+              , message = fileName ++ " is not a correct Elm file"
+              , details =
+                    [ "I could not understand the contents of this file, and this prevents me from analyzing it. It's highly likely that the contents of the file is not correct Elm code."
+                    , "Hint: Try running `elm make`. The compiler should give you better hints on how to resolve the problem."
+                    ]
+              , range = { start = { row = 0, column = 0 }, end = { row = 0, column = 0 } }
+              }
+            ]
 
 
-lintSourceWithRule : File -> Rule -> List LintError
-lintSourceWithRule file rule =
+lintSourceWithRule : String -> File -> Rule -> List LintError
+lintSourceWithRule fileName file rule =
     Rule.analyzer rule file
-        |> List.map (errorToRuleError Nothing rule)
+        |> List.map (ruleErrorToLintError fileName rule)
 
 
 compareErrorPositions : LintError -> LintError -> Order
@@ -109,8 +119,8 @@ compareRange a b =
         EQ
 
 
-errorToRuleError : Maybe String -> Rule -> Rule.Error -> LintError
-errorToRuleError file rule error =
+ruleErrorToLintError : String -> Rule -> Rule.Error -> LintError
+ruleErrorToLintError file rule error =
     { file = file
     , ruleName = Rule.name rule
     , message = Rule.errorMessage error
@@ -121,11 +131,9 @@ errorToRuleError file rule error =
 
 {-| Parse source code into a AST
 -}
-parseSource : String -> Result (List String) File
+parseSource : String -> Result String File
 parseSource source =
     source
         |> Parser.parse
-        -- TODO Improve parsing error handling
-        |> Result.mapError (\error -> [ "Parsing error" ])
-        -- TODO Add all files to have more context https://package.elm-lang.org/packages/stil4m/elm-syntax/latest/Elm-Processing
+        |> Result.mapError (\error -> "Parsing error")
         |> Result.map (process init)

src/Lint/Test.elm

@@ -135,14 +135,19 @@ You can't just have an expression like `1 + 2`.
 
 -}
 run : Rule -> String -> LintResult
-run rule sourceCode =
-    case lintSource [ rule ] sourceCode of
-        Ok errors ->
-            SuccessfulRun
-                { getCodeAtLocation = getCodeAtLocationInSourceCode sourceCode
-                , checkIfLocationIsAmbiguous = checkIfLocationIsAmbiguousInSourceCode sourceCode
-                }
-                (List.map
+run rule source =
+    let
+        errors : List Lint.LintError
+        errors =
+            lintSource [ rule ] { fileName = "TestContent.elm", source = source }
+    in
+    case List.head errors |> Maybe.map .message of
+        Just "TestContent.elm is not a correct Elm file" ->
+            ParseFailure
+
+        _ ->
+            errors
+                |> List.map
                     (\error_ ->
                         Rule.error
                             { message = error_.message
@@ -150,11 +155,10 @@ run rule sourceCode =
                             }
                             error_.range
                     )
-                    errors
-                )
-
-        Err _ ->
-            ParseFailure
+                |> SuccessfulRun
+                    { getCodeAtLocation = getCodeAtLocationInSourceCode source
+                    , checkIfLocationIsAmbiguous = checkIfLocationIsAmbiguousInSourceCode source
+                    }
 
 
 {-| Assert that the rule reported no errors. Note, this is equivalent to using [`expectErrors`](#expectErrors)