check type stability in CI (#63)

* check type stability

* add dependency

* move to extras

Project.toml

@@ -42,6 +42,7 @@ julia = "^1.3"
 MD5 = "6ac74813-4b46-53a4-afec-0b5dc9d7885c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 ThreadsX = "ac1d9e8a-700a-412c-b207-f0111f4b6c0d"
+InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
 
 [targets]
-test = ["Test", "ThreadsX", "MD5"]
+test = ["Test", "ThreadsX", "MD5", "InteractiveUtils"]

test/runtests.jl

@@ -1,6 +1,7 @@
 using Test
 using UnROOT, LorentzVectors
 using StaticArrays
+using InteractiveUtils
 using MD5
 
 @static if VERSION > v"1.3.0"
@@ -413,3 +414,27 @@ end
     @test all(ids_jagged[1] .== collect(1:56))
     @test all(ids_jagged[9] .== collect(1:54))
 end
+
+@testset "Type stability" begin
+    function isfullystable(func)
+        io = IOBuffer()
+        print(io, (@code_typed func()).first);
+        typed = String(take!(io))
+        return !occursin("::Any", typed)
+    end
+
+    rootfile = ROOTFile(joinpath(SAMPLES_DIR, "NanoAODv5_sample.root"))
+    t = LazyTree(rootfile, "Events", ["MET_pt"])[1:10]
+
+    function f1()
+        s = 0.0f0
+        for evt in t
+            s += evt.MET_pt
+        end
+        s
+    end
+    f2() = sum(t.MET_pt)
+
+    @test isfullystable(f1)
+    @test isfullystable(f2)
+end