diff --git a/test/io/test_all.jl b/test/io/test_all.jl
index 9894b62..b681b65 100644
--- a/test/io/test_all.jl
+++ b/test/io/test_all.jl
@@ -10,4 +10,5 @@ Test.@testset "io" begin
     include("test_get_signal_prior_info.jl")
     include("test_get_energy_scale_pars.jl")
     include("test_get_efficiency.jl")
+    include("test_event_is_contained.jl")
 end
diff --git a/test/io/test_event_is_contained.jl b/test/io/test_event_is_contained.jl
new file mode 100644
index 0000000..f21710e
--- /dev/null
+++ b/test/io/test_event_is_contained.jl
@@ -0,0 +1,33 @@
+using Pkg
+Pkg.activate(".") # activate the environment
+Pkg.instantiate() # instantiate the environment
+include("../../src/ZeroNuFit.jl")
+using .ZeroNuFit
+include("../../main.jl")
+include("../../src/utils.jl")
+
+@testset "" begin
+
+    @info "Testing function to flag if an event is contained or not in the fit ranges (function 'event_is_contained' in src/utils.jl)"
+    fit_range = [[1930.0, 2098.511], [2108.511, 2113.513], [2123.513, 2190.0]]
+
+    # contained event
+    event = 1950.0
+    flag = nothing
+    try
+        flag = ZeroNuFit.event_is_contained(event, fit_range)
+    catch e
+        @error "Error in event_is_contained: $e"
+        throw(e)
+    end
+
+    @testset "Check flag is valid" begin
+        @test !isnothing(flag)
+    end
+    @test flag == true
+
+    # event outside fit window
+    event = 150.0
+    flag = ZeroNuFit.event_is_contained(event, fit_range)
+    @test flag == false
+end