add tests

Author: simeonschaub

test/constructed_images.jl

@@ -359,4 +359,20 @@ mutable struct TestType end
         img = ImageMagick.load("images/cameraman.tif")
         @test size(img) == (512, 512)
     end
+
+    if VERSION >= v"1.6" || Sys.which("gs") !== nothing
+        @testset "PDF" begin
+            pdf = ImageMagick.load("images/FLAT_-_What_is_Creative_Commons.pdf")
+            @test size(pdf) == (405, 720, 10)
+
+            fn = joinpath(workdir, "cc.pdf")
+            ImageMagick.save(fn, pdf)
+            @test ImageMagick.load(fn) == pdf
+
+            pdf_100dpi = ImageMagick.load("images/FLAT_-_What_is_Creative_Commons.pdf"; dpi=100)
+            @test size(pdf_100dpi) == (563, 1000, 10)
+        end
+    else
+        @warn "skipping PDF tests"
+    end
 end