Improve coverage

Author: mtfishman

test/test_blockindices.jl

@@ -91,6 +91,7 @@ import BlockArrays: BlockIndex, BlockIndexRange, BlockSlice
         @test Block(1,1)[1:2,1:2] == BlockIndexRange(Block(1,1),(1:2,1:2))
         @test Block(1)[1:3][1:2] == BlockIndexRange(Block(1),1:2)
         @test Block(1,1)[2:4,2:4][2:3,2:3] == BlockIndexRange(Block(1,1),(3:4,3:4))
+        @test BlockIndexRange(Block(),())[] == BlockIndex()
         @test BlockIndex((2,2,2),(2,)) == BlockIndex((2,2,2),(2,1,)) == BlockIndex((2,2,2),(2,1,1))
         @test BlockIndex(2,(2,)) === BlockIndex((2,),(2,))
         @test BlockIndex(UInt(2),(2,)) === BlockIndex((UInt(2),),(2,))