add show tests

Author: ablaom

src/backends.jl

@@ -118,7 +118,7 @@ end
 function Base.show(io::IO, ::MIME"text/plain", observations::SageObs)
     A = observations.features
     y = observations.target
-    println(io, "SaffronObs")
+    println(io, "SageObs")
     println(io, "  features :: $(typeof(A))($(size(A)))")
     println(io, "  names: $(observations.names)")
     println(io, "  target :: $(typeof(y))($(size(y)))")

src/tarragon.jl

@@ -186,3 +186,9 @@ end
 
 # involutivity:
 obs(model, observations::BasicObs, ::Tarragon) = observations
+
+# data deconstructors:
+LearnAPI.features(learner, observations::BasicObs, ::Tarragon) =
+    BasicObs(observations.features, observations.names)
+LearnAPI.features(learner, data, frontend::Tarragon) =
+    LearnAPI.features(learner, obs(learner, data), frontend)

test/backends.jl

@@ -0,0 +1,25 @@
+using Test
+using LearnDataFrontEnds
+import CategoricalArrays
+
+@testset "show methods" begin
+    x = fill(0,2,3)
+    y = [3, 2, 1]
+    names = [:x1, :x2]
+    ycat = CategoricalArrays.categorical(y)
+    c = LearnDataFrontEnds.classes(ycat)
+    d = LearnDataFrontEnds.decoder(ycat)
+    mime =  MIME"text/plain"()
+
+    @test sprint(show, mime, LearnDataFrontEnds.BasicObs(x, names)) ==
+        "BasicObs\n  features :: Matrix{Int64}((2, 3))\n  names: [:x1, :x2]\n"
+    @test sprint(show, mime, LearnDataFrontEnds.SaffronObs(x, names, y)) ==
+        "SaffronObs\n  features :: Matrix{Int64}((2, 3))\n  names: "*
+        "[:x1, :x2]\n  target :: Vector{Int64}((3,))"
+    @test sprint(show, mime, LearnDataFrontEnds.SageObs(x, names, y, c, d)) ==
+        "SageObs\n  features :: Matrix{Int64}((2, 3))\n  names: "*
+        "[:x1, :x2]\n  target :: Vector{Int64}((3,))\n  classes_seen: "*
+        "[1, 2, 3] (categorical vector with complete pool)\n  decoder: <callable>"
+end
+
+true

test/runtests.jl

@@ -2,6 +2,7 @@ using Test
 
 test_files = [
     "tools.jl",
+    "backends.jl",
     "saffron.jl",
     "sage.jl",
     "tarragon.jl",