add metabolite feature (#124)

* add metabolite feature

* remove qualifier

src/Microbiome.jl

@@ -4,6 +4,7 @@ module Microbiome
 export MicrobiomeSample,
        Taxon,
        GeneFunction,
+       Metabolite,
        metadata,
        set!,
        unset!,
@@ -14,7 +15,10 @@ export MicrobiomeSample,
        hasrank,
        taxon,
        hastaxon,
-       genefunction
+       genefunction,
+       commonname,
+       masscharge,
+       retentiontime
 
 # EcoBase Translations
 export abundances,
@@ -76,10 +80,6 @@ using ReTest
 import Dictionaries: set!, unset!, insert!, delete!
 import Base: ==
 
-@testset "test" begin
-    @test true
-end
-
 include("ecobase.jl")
 include("samples.jl")
 include("features.jl")

src/features.jl

@@ -180,4 +180,32 @@ function genefunction(n::AbstractString)
     end
 end
 
-Base.string(f::AbstractFeature) = String(f)
+Base.string(f::AbstractFeature) = String(f)
+
+struct Metabolite <: AbstractFeature
+    name::String
+    commonname::Union{Missing, String}
+    mz::Union{Missing, Float64}
+    rt::Union{Missing, Float64}
+end
+
+Metabolite(n::AbstractString) = Metabolite(n, missing, missing, missing)
+
+name(m::Metabolite) = m.name
+commonname(m::Metabolite) = m.commonname
+masscharge(m::Metabolite) = m.mz
+retentiontime(m::Metabolite) = m.rt
+
+@testset "Metabolites" begin
+    m1 = Metabolite("name", "common", 1., 1.)
+    @test name(m1) == "name"
+    @test commonname(m1) == "common"
+    @test masscharge(m1) == 1
+    @test retentiontime(m1) == 1
+    m2 = Metabolite("name")
+    @test name(m2) == "name"
+    @test ismissing(commonname(m2))
+    @test ismissing(masscharge(m2))
+    @test ismissing(masscharge(m2))
+
+end