handle non existant memory values even in memory output

lib/benchee/formatters/console/memory.ex

@@ -12,6 +12,7 @@ defmodule Benchee.Formatters.Console.Memory do
     Conversion,
     Conversion.Unit,
     Conversion.Count,
+    Conversion.Memory,
     Formatters.Console.Helpers
   }
 
@@ -114,8 +115,29 @@ defmodule Benchee.Formatters.Console.Memory do
     end)
   end
 
+  @na "N/A"
+
   @spec format_scenario(Scenario.t(), unit_per_statistic, integer, boolean) :: String.t()
+  defp format_scenario(scenario, units, label_width, hide_statistics)
+
+  defp format_scenario(
+         scenario = %Scenario{memory_usage_statistics: %{sample_size: 0}},
+         _,
+         label_width,
+         _) do
+
+    "~*ts~*ts\n"
+    |> :io_lib.format([
+      -label_width,
+      scenario.name,
+      @average_width,
+      @na
+    ])
+    |> to_string
+  end
+
   defp format_scenario(scenario, %{memory: memory_unit}, label_width, false) do
+    # IO.inspect(scenario)
     %Scenario{
       name: name,
       memory_usage_statistics: %Statistics{
@@ -205,13 +227,18 @@ defmodule Benchee.Formatters.Console.Memory do
     end)
   end
 
-  defp calculate_slower_value(0, _), do: "N/A"
-  defp calculate_slower_value(_, 0), do: "N/A"
-  defp calculate_slower_value(job_median, reference_median), do: job_median / reference_median
+  defp calculate_slower_value(job_median, reference_median)
+        when job_median == 0 or is_nil(job_median) or reference_median == 0 or
+               is_nil(reference_median) do
+    @na
+  end
+  defp calculate_slower_value(job_median, reference_median) do
+    job_median / reference_median
+  end
 
-  defp format_comparison(scenario, %{memory: memory_unit}, label_width, "N/A") do
+  defp format_comparison(scenario, %{memory: memory_unit}, label_width, @na) do
     %Scenario{name: name, memory_usage_statistics: %Statistics{median: median}} = scenario
-    median_format = Helpers.duration_output(median, memory_unit)
+    median_format = memory_output(median, memory_unit)
 
     "~*s~*s\n"
     |> :io_lib.format([-label_width, name, @median_width, median_format])
@@ -227,6 +254,12 @@ defmodule Benchee.Formatters.Console.Memory do
     |> to_string
   end
 
+  defp memory_output(nil, _unit), do: "N/A"
+
+  defp memory_output(memory, unit) do
+    Memory.format({Memory.scale(memory, unit), unit})
+  end
+
   defp extended_statistics_report(_, _, _, %{extended_statistics: false}, _), do: []
   defp extended_statistics_report(_, _, _, _, true), do: []
 

test/benchee/formatters/console/memory_test.exs

@@ -299,6 +299,83 @@ defmodule Benchee.Formatters.Console.MemoryTest do
 
       assert [] = Memory.format_scenarios(scenarios, %{})
     end
+
+    test "it doesn't blow up if some of the values have no statistics (yes that happened)" do
+      scenarios = [
+        %Scenario{
+          name: "First",
+          memory_usage_statistics: %Statistics{
+            average: 100.0,
+            std_dev: 0.0,
+            std_dev_ratio: 0.0,
+            median: 100.0,
+            percentiles: %{99 => 100.0},
+            sample_size: 10
+          },
+          run_time_statistics: %Statistics{}
+        },
+        %Scenario{
+          name: "Second",
+          memory_usage_statistics: %Statistics{},
+          run_time_statistics: %Statistics{}
+        }
+      ]
+
+      output =
+        Enum.join(
+          Memory.format_scenarios(scenarios, %{
+            comparison: true,
+            unit_scaling: :best,
+            extended_statistics: false
+          })
+        )
+
+      assert output =~ "First"
+      assert output =~ ~r/Second.+N\/A/i
+      assert output =~ "N/A"
+    end
+
+    test "it doesn't blow up if some come back with a median of 0.0" do
+      scenarios = [
+        %Scenario{
+          name: "First",
+          memory_usage_statistics: %Statistics{
+            average: 0.0,
+            median: 0.0,
+            sample_size: 10,
+            percentiles: %{99 => 0.0},
+            std_dev: 0.0,
+            std_dev_ratio: 0.0
+          },
+          run_time_statistics: %Statistics{}
+        },
+        %Scenario{
+          name: "Second",
+          memory_usage_statistics: %Statistics{
+            average: 100.0,
+            median: 100.0,
+            sample_size: 5,
+            percentiles: %{99 => 100.0},
+            std_dev: 5.0,
+            std_dev_ratio: 0.10
+          },
+          run_time_statistics: %Statistics{}
+        }
+      ]
+
+      output =
+        Enum.join(
+          Memory.format_scenarios(scenarios, %{
+            comparison: true,
+            unit_scaling: :best,
+            extended_statistics: false
+          })
+        )
+
+      assert output =~ "First"
+      assert output =~ "Second"
+      refute output =~ "x memory usage"
+    end
   end
 
   defp assert_column_width(name, string, expected_width) do