diff --git a/test/dependent.jl b/test/dependent.jl
index 1a6b3c9..2c97cbe 100644
--- a/test/dependent.jl
+++ b/test/dependent.jl
@@ -26,6 +26,12 @@ r15 = S.Rule(S.Clause(" X[i, 1] ≥ 32000 & X[i, 4] < 12 "), [0.192], [0.096])
 r16 = S.Rule(S.Clause(" X[i, 2] ≥ 8000 & X[i, 4] ≥ 12 "), [0.586], [0.076])
 r17 = S.Rule(S.Clause(" X[i, 2] ≥ 8000 & X[i, 4] < 12 "), [0.236], [0.094])
 
+@test S._gap_size(r1) == 0.408 - 0.061
+@test S._gap_size(r3) == 0.386 - 0.062
+@test S._gap_size(r3) < S._gap_size(r1)
+@test S._gap_size(r12) < S._gap_size(r1)
+
+@test S._sort_by_gap_size([r3, r12, r1]) == [r1, r3, r12]
 @test S._filter_linearly_dependent([r1, r2, r3, r5]) == [r1, r3, r5]
 
 let