Add tests for pipes

test/pipes.jl

@@ -0,0 +1,16 @@
+using Test
+using Interpolations
+
+@testset "Pipes" begin
+    for BC in (Throw, Flat, Line, Free, Reflect, InPlace, InPlaceQ, Periodic)
+        for GT in (OnGrid, OnCell)
+            @test BC(GT) == BC(GT())
+            @test GT |> BC == BC(GT())
+            for D in (Cubic, Quadratic)
+                @test GT |> BC |> D == D(BC(GT()))
+                @test GT |> BC |> D{BC{GT}} == D(BC(GT()))
+            end
+        end
+    end
+    @test BSpline() == BSpline(Linear())
+end