Add @test_reference_plot

Project.toml

@@ -9,6 +9,7 @@ Distances = "b4f34e82-e78d-54a5-968a-f98e89d6e8f7"
 FileIO = "5789e2e9-d7fb-5bc7-8068-2c6fae9b9549"
 ImageCore = "a09fc81d-aa75-5fe9-8630-4744c3626534"
 ImageInTerminal = "d8c32880-2388-543b-8c61-d9f865259254"
+PNGFiles = "f57f5aa1-a3ce-4bc8-8ab9-96f992907883"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 SHA = "ea8e919c-243c-51af-8825-aaa63cd721ce"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
@@ -23,6 +24,7 @@ ImageCore = "0.8.1"
 ImageInTerminal = "0.3, 0.4"
 ImageMagick = "0.7, 1"
 ImageTransformations = "0.8"
+PNGFiles = "0.3"
 TestImages = "0.6, 1"
 julia = "1"
 
@@ -31,7 +33,8 @@ CSVFiles = "5d742f6a-9f54-50ce-8119-2520741973ca"
 DataFrames = "a93c6f00-e57d-5684-b7b6-d8193f3e46c0"
 ImageMagick = "6218d12a-5da1-5696-b52f-db25d2ecc6d1"
 ImageTransformations = "02fcd773-0e25-5acc-982a-7f6622650795"
+Plots = "91a5bcdd-55d7-5caf-9e0b-520d859cae80"
 TestImages = "5e47fb64-e119-507b-a336-dd2b206d9990"
 
 [targets]
-test = ["CSVFiles", "DataFrames", "ImageMagick", "ImageTransformations", "TestImages"]
+test = ["CSVFiles", "DataFrames", "ImageMagick", "ImageTransformations", "Plots", "TestImages"]

src/ReferenceTests.jl

@@ -4,6 +4,7 @@ using Test
 using ImageCore
 using Distances
 using FileIO
+using PNGFiles
 using ImageInTerminal
 using SHA
 using DeepDiffs
@@ -13,10 +14,12 @@ export
     @withcolor,
     @io2str,
     @test_reference,
+    @test_reference_plot,
     psnr_equality
 
 include("utils.jl")
 include("test_reference.jl")
+include("test_reference_plot.jl")
 include("fileio.jl")
 include("equality_metrics.jl")
 include("render.jl")

src/test_reference_plot.jl

@@ -0,0 +1,23 @@
+"""
+    @test_reference_plot filename plot [by] [kw...]
+
+Tests that the `plot` with reference `filename` using
+equality test strategy `by`. The macro simply converts
+the plot object to a PNG image and forwards it to the
+[`@test_reference`](@ref) macro.
+"""
+macro test_reference_plot(reference, actual, kws...)
+    ref = esc(reference)
+    plt = esc(actual)
+    opt = esc(kws)
+    :(@test_reference $ref asimage($plt))
+end
+
+# helper function to convert a Plots.jl plot
+# into an image for visual comparison
+function asimage(plt)
+    io = IOBuffer()
+    show(io, "image/png", plt)
+    seekstart(io)
+    PNGFiles.load(io)
+end

test/runtests.jl

@@ -1,6 +1,12 @@
-using Test
-using ImageInTerminal, TestImages, ImageCore, ImageTransformations
-using Random
+using Test, Random
+using TestImages
+using ImageCore
+using ImageInTerminal
+using ImageTransformations
+using Plots
+
+# workaround GR warnings
+ENV["GKSwstype"] = "100"
 
 if isinteractive()
     @info ("In interactive use, one should respond \"n\" when the program"
@@ -150,4 +156,9 @@ end
     rm(newfilename, force=true)
 end
 
+@testset "Plots as PNG images" begin
+    @test_reference_plot "references/heatmap.png" heatmap([1 0; 0 1])
+    @test_reference_plot "references/scatter.png" scatter([(0,0),(1,0),(0,1),(1,1)],ms=8)
+end
+
 end  # top level testset