Added tests to check correct return type for @bs

Author: ajinkya-k

test/runtests.jl

@@ -8,4 +8,5 @@ using Test
     @test startswith(s, r"Chairmarks\.Benchmark: [0-9]* samples? with [0-9]* evaluations?\.")
     @test endswith(s, "allocs estimate: 0.")
     @test occursin(r"Histogram: (log\()?frequency\)? by time", s)
+    bb = @bs sleep(0.001), sleep(0.01); @test (bb isa Tuple)
 end