Check type of main function

1 files changed, 25 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/config/ConfigCheckerTests.java b/src/test/java/org/shedlang/compiler/config/ConfigCheckerTests.java
index b6134ed2..404e57e6 100644
--- a/src/test/java/org/shedlang/compiler/config/ConfigCheckerTests.java
+++ b/src/test/java/org/shedlang/compiler/config/ConfigCheckerTests.java
@@ -66,4 +66,29 @@ public class ConfigCheckerTests {
 
         assertThat(error.getMessage(), equalTo("Namespace Main has no field main"));
     }
+
+    @Test
+    public void whenMainFunctionHasWrongTypeThenBinConfigIsInvalid() throws IOException {
+        var binConfig = new BinConfig("x", NamespaceName.of("Main"));
+        var typeInfos = TypeInfos.EMPTY
+            .addNamespaceTypeInfo(
+                NamespaceName.of("Main"),
+                NamespaceTypeInfo.fromFields(P.orderedMap(
+                    Map.entry(
+                        "main",
+                        new FunctionType(List.of(), List.of(), Effects.IO, Types.STRING)
+                    )
+                ))
+            );
+
+        var error = assertThrows(
+            ConfigError.class,
+            () -> ConfigChecker.configCheckBin(binConfig, typeInfos)
+        );
+
+        assertThat(
+            error.getMessage(),
+            equalTo("main function should have type fn () ! Io -> Unit, but Main.main has type fn () ! Io -> String")
+        );
+    }
 }