Use abspath on filenames (fixes #23)

Author: timholy

src/CodeTracking.jl

@@ -114,6 +114,7 @@ Return the signatures of all methods whose definition spans the specified locati
 Returns `nothing` if there are no methods at that location.
 """
 function signatures_at(filename::AbstractString, line::Integer)
+    filename = abspath(filename)
     if occursin(juliabase, filename)
         rpath = postpath(filename, juliabase)
         id = PkgId(Base)

test/runtests.jl

@@ -4,7 +4,7 @@ using CodeTracking
 using Test, InteractiveUtils
 # Note: ColorTypes needs to be installed, but note the intentional absence of `using ColorTypes`
 
-include("script.jl")
+isdefined(Main, :Revise) ? includet("script.jl") : include("script.jl")
 
 @testset "CodeTracking.jl" begin
     m = first(methods(f1))
@@ -87,5 +87,8 @@ end
         @test !isempty(sigs)
         sigs = signatures_at(Base.find_source_file(String(m.file)), m.line)
         @test !isempty(sigs)
+
+        # issue #23
+        @test !isempty(signatures_at("script.jl", 9))
     end
 end