test support for non-continuous terms (e.g., categorical0 (#10)

src/centering.jl

@@ -149,7 +149,15 @@ function center(t::AbstractTerm, c::Center)
 end
 
 StatsModels.modelcols(t::CenteredTerm, d::NamedTuple) = modelcols(t.term, d) .- t.center
-StatsBase.coefnames(t::CenteredTerm) = "$(coefnames(t.term))(centered: $(t.center))"
+function StatsBase.coefnames(t::CenteredTerm)
+    if StatsModels.width(t.term) == 1
+        return "$(coefnames(t.term))(centered: $(t.center))"
+    elseif length(t.center) > 1
+        return string.(vec(coefnames(t.term)), "(centered: ", vec(t.center), ")")
+    else
+        return string.(coefnames(t.term), "(centered: ", t.center, ")")
+    end
+end
 # coef table: "x: centered at 5.5"
 Base.show(io::IO, t::CenteredTerm) = show(io, t.term)
 # regular show: "x"

test/centering.jl

@@ -53,6 +53,7 @@
         xc2 = center(x, Center(2))
         xc22 = center(x, 2)
         @test xc2.center == xc22.center == 2
+
     end
 
     @testset "plays nicely with formula" begin
@@ -82,4 +83,23 @@
         @test coefnames(xc) == "x(centered: 5.5)"
     end
 
+    @testset "categorical term" begin
+        z = concrete_term(term(:z), data)
+        @test_throws ArgumentError center(z)
+        @test_throws ArgumentError center(z, Center())
+        zc = center(z, Center(0.5))
+        @test modelcols(zc, data) == modelcols(z, data) .- 0.5
+        @test StatsModels.width(zc) == StatsModels.width(z)
+        @test coefnames(zc) == coefnames(z) .* "(centered: 0.5)"
+
+        zc2 = center(z, Center([1 2 3 4]))
+        @test modelcols(zc2, data) == modelcols(z, data) .- [1 2 3 4]
+        @test coefnames(zc2) == coefnames(z) .* "(centered: " .* string.([1, 2, 3, 4]) .* ")"
+    end
+
+    # @testset "utilities" begin
+
+
+    # end
+
 end