Add and test some missing interface functions

src/vector_of_array.jl

@@ -426,12 +426,34 @@ function Base.copy(VA::AbstractDiffEqArray)
         (VA.sys === nothing) ? nothing : copy(VA.sys))
 end
 Base.copy(VA::AbstractVectorOfArray) = typeof(VA)(copy(VA.u))
+
+Base.zero(VA::VectorOfArray) = VectorOfArray(Base.zero.(VA.u))
+
+function Base.zero(VA::DiffEqArray)
+    u = Base.zero.(VA.u)
+    DiffEqArray(u, VA.t, VA.p, VA.sys)
+end
+
 Base.sizehint!(VA::AbstractVectorOfArray{T, N}, i) where {T, N} = sizehint!(VA.u, i)
 
 Base.reverse!(VA::AbstractVectorOfArray) = reverse!(VA.u)
 Base.reverse(VA::VectorOfArray) = VectorOfArray(reverse(VA.u))
 Base.reverse(VA::DiffEqArray) = DiffEqArray(reverse(VA.u), VA.t, VA.p, VA.sys)
 
+function Base.resize!(VA::AbstractVectorOfArray, i::Integer)
+    if Base.hasproperty(VA, :sys) && VA.sys !== nothing
+        error("resize! is not allowed on AbstractVectorOfArray with a sys")
+    end
+    Base.resize!(VA.u, i)
+    if Base.hasproperty(VA, :t) && VA.t !== nothing
+        Base.resize!(VA.t, i)
+    end
+end
+
+function Base.pointer(VA::AbstractVectorOfArray)
+    Base.pointer(VA.u)
+end
+
 function Base.push!(VA::AbstractVectorOfArray{T, N}, new_item::AbstractArray) where {T, N}
     push!(VA.u, new_item)
 end

test/interface_tests.jl

@@ -112,3 +112,8 @@ A = VectorOfArray(map(i -> rand(2, 4), 1:7))
 
 DA = DiffEqArray(map(i -> rand(2, 4), 1:7), 1:7)
 @test map(x -> maximum(x), DA) isa Vector
+
+u = VectorOfArray([fill(2, SVector{2, Float64}), ones(SVector{2, Float64})])
+@test typeof(zero(u)) <: typeof(u)
+resize!(u,3)
+@test pointer(u) === pointer(u.u)