fix guideline (should return message also)

src/AutoMerge/guidelines.jl

@@ -412,9 +412,17 @@ const guideline_name_identifier = Guideline(;
     docs=string(
         "The package name should be a valid Julia identifier (according to `Base.isidentifier`).",
     ),
-    check=data -> Base.isidentifier(data.pkg),
+    check=data -> meets_name_is_identifier(data.pkg),
 )
 
+function meets_name_is_identifier(pkg)
+    if Base.isidentifier(pkg)
+        return true, ""
+    else
+        return false, "The package's name ($pkg) is not a valid Julia identifier according to `Base.isidentifier`. Typically this means it contains `-` or other characters that can't be used in defining a variable name or module. The package must be renamed to be registered."
+    end
+end
+
 const guideline_normal_capitalization = Guideline(;
     info="Normal capitalization",
     docs=string(

test/automerge-unit.jl

@@ -76,6 +76,10 @@ end
 end
 
 @testset "Guidelines for new packages" begin
+    @testset "Package name is a valid identifier" begin
+        @test AutoMerge.meets_name_is_identifier("Hello")[1]
+        @test !AutoMerge.meets_name_is_identifier("Hello-GoodBye")[1]
+    end
     @testset "Normal capitalization" begin
         @test AutoMerge.meets_normal_capitalization("Zygote")[1]  # Regular name
         @test AutoMerge.meets_normal_capitalization("Zygote")[1]