Add test and fix handling of invalid go.mod

Author: tjugdev

src/Strategy/Go/Gomod.hs

@@ -53,11 +53,11 @@ import Text.Megaparsec (
   MonadParsec (eof, takeWhile1P, try),
   Parsec,
   between,
+  choice,
   chunk,
   count,
   many,
   oneOf,
-  option,
   optional,
   parse,
   sepBy,
@@ -220,16 +220,22 @@ gomodParser :: Parser Gomod
 gomodParser = do
   _ <- scn
   (name, statements) <-
-    option
-      ("empty module", [])
-      ( do
-          _ <- lexeme (chunk "module")
-          name <- modulePath
-          _ <- scn
-          statements <- many (statement <* scn)
-          eof
-          pure (name, statements)
-      )
+    choice
+      [ -- Non-empty go.mod file
+        ( do
+            _ <- lexeme (chunk "module")
+            name <- modulePath
+            _ <- scn
+            statements <- many (statement <* scn)
+            eof
+            pure (name, statements)
+        )
+      , -- Empty go.mod file
+        ( do
+            eof
+            pure ("", [])
+        )
+      ]
 
   let statements' = concat statements
 

test/Go/GomodSpec.hs

@@ -7,15 +7,15 @@ import Data.Function ((&))
 import Data.Map.Strict qualified as Map
 import Data.SemVer (version)
 import Data.SemVer.Internal (Identifier (..))
-import Data.Text (Text)
+import Data.Text (Text, empty)
 import Data.Text.IO qualified as TIO
 import DepTypes (DepType (GoType), Dependency (..), VerConstraint (CEq))
 import Effect.Grapher (direct, evalGrapher)
 import Graphing (Graphing (..))
 import Strategy.Go.Gomod (Gomod (..), PackageVersion (..), Require (..), buildGraph, gomodParser)
 import Strategy.Go.Types (graphingGolang)
 import Test.Hspec (Spec, describe, it, runIO, shouldBe)
-import Test.Hspec.Megaparsec (shouldParse)
+import Test.Hspec.Megaparsec (shouldFailOn, shouldParse)
 import Text.Megaparsec (runParser)
 import Text.RawString.QQ (r)
 
@@ -57,6 +57,16 @@ trivialGraph = run . evalGrapher $ do
   direct $ dep "github.com/pkg/overridden" "overridden"
   direct $ dep "github.com/pkg/three/v3" "v3.0.0"
 
+emptyGomod :: Gomod
+emptyGomod =
+  Gomod
+    { modName = ""
+    , modRequires = []
+    , modReplaces = Map.empty
+    , modLocalReplaces = Map.empty
+    , modExcludes = []
+    }
+
 localReplaceGomod :: Gomod
 localReplaceGomod =
   Gomod
@@ -193,6 +203,9 @@ spec_parse = do
     it "parses a trivial example" $ do
       runParser gomodParser "" trivialInput `shouldParse` trivialGomod
 
+    it "parses empty go.mod" $ do
+      runParser gomodParser "" Data.Text.empty `shouldParse` emptyGomod
+
     it "parses each edge case" $ do
       runParser gomodParser "" edgecaseInput `shouldParse` edgeCaseGomod
 
@@ -211,6 +224,9 @@ spec_parse = do
       runParser gomodParser "" goModWithRetractComment3 `shouldParse` gomodWithRetract
       runParser gomodParser "" goModWithRetractComment4 `shouldParse` gomodWithRetract
 
+    it "fails to parse invalid go.mod" $ do
+      runParser gomodParser "" `shouldFailOn` "invalid input"
+
 gomodWithRetract :: Gomod
 gomodWithRetract =
   Gomod