From c96f9b523ab919fb88cbe01379ad13f876a076c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mos=C3=A8=20Giordano?= <m.giordano@ucl.ac.uk>
Date: Tue, 25 Feb 2020 18:42:55 +0000
Subject: [PATCH] Add tests for OffsetArrays

---
 base/abstractarray.jl |  4 ++--
 test/offsetarray.jl   | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index e1c0c1574b5a5..f654bd8bdf196 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -362,7 +362,7 @@ julia> first(Bool[], 1)
 0-element Array{Bool,1}
 ```
 """
-first(v::AbstractVector, n::Integer) = @inbounds v[firstindex(v):min(firstindex(v) - 1 + n, end)]
+first(v::AbstractVector, n::Integer) = @inbounds v[firstindex(v):min(firstindex(v) + n - 1, end)]
 
 """
     last(coll)
@@ -401,7 +401,7 @@ julia> last(Float64[], 1)
 0-element Array{Float64,1}
 ```
 """
-last(v::AbstractArray, n::Integer) = @inbounds v[max(firstindex(v), end + 1 - n):end]
+last(v::AbstractArray, n::Integer) = @inbounds v[max(firstindex(v), end - n + 1):end]
 
 """
     strides(A)
diff --git a/test/offsetarray.jl b/test/offsetarray.jl
index d8e2518e2f139..caa8199670958 100644
--- a/test/offsetarray.jl
+++ b/test/offsetarray.jl
@@ -609,3 +609,17 @@ end
     @test_throws DimensionMismatch maximum!(fill(0, -4:-4, 7:7, -6:-5, 1:1), B)
     @test_throws DimensionMismatch minimum!(fill(0, -4:-4, 7:7, -6:-5, 1:1), B)
 end
+
+@testset "first/last n elements of vector" begin
+    f = firstindex(v)
+    @test first(v, -2) == []
+    @test first(v, 2) == v[f:f+1]
+    @test first(v, 100) == v0
+    @test first(v, 100) !== v
+    @test first(v, 1) != v[f]
+    @test last(v, -2) == []
+    @test last(v, 2) == v[end-1:end]
+    @test last(v, 100) == v0
+    @test last(v, 100) !== v
+    @test last(v, 1) != v[end]
+end