Add tests

Author: kojix2

spec/reference_spec.cr

@@ -866,12 +866,30 @@ describe "Julia reference output compatibility" do
       test_ref("heatmap/default_0x0.txt", p)
     end
 
+    it "matches heatmap/default_0x5" do
+      z = [] of Array(Float64)
+      p = UnicodePlot.heatmap(z, labels: false, xlim: {1.0, 5.0})
+      test_ref("heatmap/default_0x5.txt", p)
+    end
+
+    it "matches heatmap/default_0x10" do
+      z = [] of Array(Float64)
+      p = UnicodePlot.heatmap(z, labels: false, xlim: {1.0, 10.0})
+      test_ref("heatmap/default_0x10.txt", p)
+    end
+
     it "matches heatmap/default_5x0" do
       z = Array.new(5) { [] of Float64 }
       p = UnicodePlot.heatmap(z, labels: false)
       test_ref("heatmap/default_5x0.txt", p)
     end
 
+    it "matches heatmap/default_10x0" do
+      z = Array.new(10) { [] of Float64 }
+      p = UnicodePlot.heatmap(z, labels: false)
+      test_ref("heatmap/default_10x0.txt", p)
+    end
+
     # integers_20x20: repeat(collect(1:20), outer=(1,20)) → A[i,j] = i
     it "matches heatmap/integers_20x20" do
       z = Array.new(20) { |i| Array.new(20) { |_j| (i + 1).to_f } }