add series duplicate_first test

test/series.jl

@@ -1,5 +1,6 @@
 using Rasters, Test, Dates, DimensionalData
 using Rasters.LookupArrays, Rasters.Dimensions
+include(joinpath(dirname(pathof(Rasters)), "../test/test_utils.jl"))
 
 # RasterSeries from Raster/RasterStack components
 
@@ -115,3 +116,13 @@ end
     @test occursin("Raster", sh)
     @test occursin("X", sh)
 end
+
+@testset "duplicate_first & lazy" begin
+    temporary_random_rasters(3, (10,10,3), UInt8) do filenames
+        times = Ti(DateTime.(sort(rand(UInt16, length(filenames)))))
+        series = RasterSeries(filenames, times; duplicate_first=true, lazy=true)
+        @test all(Rasters.filename.(series) .== filenames)
+        first_dims = dims(first(series))
+        @test all(dims(r) == first_dims for r in series)
+    end
+end

test/test_utils.jl

@@ -1,3 +1,5 @@
+using ArchGDAL
+
 # Loader for external sources
 maybedownload(url, filename=splitdir(url)[2]) = begin
     dirpath = joinpath(dirname(pathof(Rasters)), "../test/data")
@@ -6,3 +8,16 @@ maybedownload(url, filename=splitdir(url)[2]) = begin
     isfile(filepath) || download(url, filepath)
     filepath
 end
+
+# create `N` random rasters with eltype `type` and x,y,band size `size`
+function temporary_random_rasters(f, N, size, type=UInt8)
+    filenames = [tempname() * ".tif" for _ in 1:N]
+    try
+        for f in filenames
+            write(f, Raster(rand(type, size); dims=(X(1:size[1]), Y(1:size[2]), Band(1:size[3]))))
+        end
+        f(filenames)
+    finally
+        rm.(filenames; force=true)
+    end
+end