Test singleton containers, fix some bugs

src/NoBang/singletoncontainers.jl

@@ -13,24 +13,29 @@ function Base.getindex(v::SingletonVector, i::Integer)
 end
 
 # Define table interface as a `SingletonVector{<:NamedTuple}`:
-Tables.istable(::Type{<:SingletonVector{<:NamedTuple{names}}}) where {names} = @isdefined(names)
-Tables.rowaccess(::Type{<:SingletonVector{names}}) where {names} = @isdefined(names)
-Tables.columnaccess(::Type{<:SingletonVector{names}}) where {names} = @isdefined(names)
+Tables.istable(::Type{<:SingletonVector{<:NamedTuple{names}}}) where {names} =
+    @isdefined(names)
+Tables.rowaccess(::Type{<:SingletonVector{<:NamedTuple{names}}}) where {names} =
+    @isdefined(names)
+Tables.columnaccess(::Type{<:SingletonVector{<:NamedTuple{names}}}) where {names} =
+    @isdefined(names)
 
 Tables.rows(x::SingletonVector{<:NamedTuple}) = [x.value]
-Tables.columns(x::SingletonVector{<:NamedTuple{names}}) where names =
+Tables.columns(x::SingletonVector{<:NamedTuple{names}}) where {names} =
     NamedTuple{names}(map(x -> [x], Tuple(x.value)))
 
 
-struct SingletonDict{K, V} <: AbstractDict{K, V}
+struct SingletonDict{K,V} <: AbstractDict{K,V}
     key::K
     value::V
 end
 
 Base.iterate(d::SingletonDict) = (d.key => d.value, nothing)
 Base.iterate(d::SingletonDict, ::Nothing) = nothing
 
-function Base.getindex(d::SingletonDict{K}, key::K) where K
+function Base.getindex(d::SingletonDict{K}, key::K) where {K}
     @boundscheck d.key == key || throw(BoundsError(d, key))
     return d.value
 end
+
+Base.length(::SingletonDict) = 1

test/Project.toml

@@ -12,6 +12,7 @@ LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 Setfield = "efcf1570-3423-57d1-acb7-fd33fddbac46"
 StaticArrays = "90137ffa-7385-5640-81b9-e52037218182"
 StructArrays = "09ab397b-f2b6-538f-b94a-2f83cf4a842a"
+Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 TypedTables = "9d95f2ec-7b3d-5a63-8d20-e2491e220bb9"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"

test/test_singletoncontainers.jl

@@ -0,0 +1,56 @@
+module TestSingletonContainers
+
+using BangBang.NoBang: SingletonDict, SingletonVector
+using Tables: Tables
+using Test
+
+function test_shows(x)
+    # smoke tests
+    @test sprint(show, x) isa String
+    @test sprint(show, "text/plain", x) isa String
+    @test string(x) isa String
+end
+
+@testset "SingletonVector" begin
+    v = SingletonVector(1)
+    @test v[1] == 1
+    @test_throws BoundsError v[2]
+    @test size(v) == (1,)
+    @test collect(v)::Vector{Int} == [1]
+    test_shows(v)
+end
+
+@testset "SingletonVector as a table" begin
+    @testset for T in [
+        SingletonVector,
+        SingletonVector{Int},
+        SingletonVector{<:NamedTuple},
+        SingletonVector{NamedTuple},
+    ]
+        @test !Tables.istable(T)
+    end
+
+    @testset for T in [
+        SingletonVector{<:NamedTuple{(:a,)}},
+        SingletonVector{<:NamedTuple{(:a,),Tuple{Int}}},
+    ]
+        @test Tables.istable(T)
+        @test Tables.rowaccess(T)
+        @test Tables.columnaccess(T)
+    end
+
+    @testset begin
+        @test Tables.rows(SingletonVector((a = 1,))) == [(a = 1,)]
+        @test Tables.columns(SingletonVector((a = 1,))) == (a = [1],)
+    end
+end
+
+@testset "SingletonDict" begin
+    d = SingletonDict(:a, 1)
+    @test d[:a] == 1
+    @test_throws BoundsError d[:non_existing_key]
+    @test collect(d)::Vector{Pair{Symbol,Int}} == [:a => 1]
+    test_shows(d)
+end
+
+end  # module