add error message when using the macros on invalid expressions (#155)

Author: KristofferC

src/Debugger.jl

@@ -94,21 +94,25 @@ function _make_frame(mod, arg)
     end
 end
 
+_check_is_call(arg) = !(arg isa Expr && arg.head == :call) && throw(ArgumentError("@enter and @run should be applied to a function call"))
+
 macro make_frame(arg)
     _make_frame(__module__, arg)
 end
 
 macro enter(arg)
+    _check_is_call(arg)
     quote
-        let frame = $(_make_frame(__module__,arg))
+        let frame = $(_make_frame(__module__, arg))
             RunDebugger(frame)
         end
     end
 end
 
 macro run(arg)
+    _check_is_call(arg)
     quote
-        let frame = $(_make_frame(__module__,arg))
+        let frame = $(_make_frame(__module__, arg))
             RunDebugger(frame; initial_continue=true)
         end
     end

test/misc.jl

@@ -86,3 +86,8 @@ import InteractiveUtils
     @test JuliaInterpreter.Variable(@__FILE__, :file, false) in locals
     @test JuliaInterpreter.Variable(LINE, :line, false) in locals
 end
+
+# These are LoadError because the error happens at macro expansion
+@test_throws LoadError @macroexpand @enter "foo"
+@test_throws LoadError @macroexpand @enter 1
+@test_throws LoadError @macroexpand @run [1,2]