Add experimental support for CSV and TSV parsing

Related to #5

.dialyzer_ignore.exs

@@ -5,4 +5,6 @@
 #
 # More info in the Dialyxir README:
 # https://github.com/jeremyjh/dialyxir#elixir-term-format
-[]
+[
+  {"deps/nimble_csv/lib/nimble_csv.ex", :unmatched_return}
+]

CHANGELOG.md

@@ -2,24 +2,26 @@
 
 ## v0.1.0
 
-Renamed to `ParameterizedTest`, with the accompanying macro `param_test`.
-(Why not `parameterized_test`? It's longer, harder to spell, and there are a lot of
-other accepted spellings, including "parameterised," "parametrized," and "parametrised.")
+- Renamed to `ParameterizedTest`, with the accompanying macro `param_test`.
+    (Why not `parameterized_test`? It's longer, harder to spell, and there are a lot of
+    other accepted spellings, including "parameterised," "parametrized," and "parametrised.")
+- Added support for hand-rolled lists of parameters, like:
 
-Added support for hand-rolled lists of parameters, like:
-
-```elixir
-param_test "shipping policy matches the web site",
-            [
-              # Items in the parameters list can be either maps...
-              %{spending_by_category: %{pants: 29_99}, coupon: "FREE_SHIP"},
-              # ...or keyword lists
-              [spending_by_category: %{shoes: 19_99, pants: 29_99}, coupon: nil]
-            ],
-            %{spending_by_category: spending_by_category, coupon: coupon} do
-  ...
-end
-```
+    ```elixir
+    param_test "shipping policy matches the web site",
+                [
+                # Items in the parameters list can be either maps...
+                %{spending_by_category: %{pants: 29_99}, coupon: "FREE_SHIP"},
+                # ...or keyword lists
+                [spending_by_category: %{shoes: 19_99, pants: 29_99}, coupon: nil]
+                ],
+                %{spending_by_category: spending_by_category, coupon: coupon} do
+    ...
+    end
+    ```
+- Added experimental support for populating test parameters from CSV and TSV files.
+  Eventually I'd like to extend this to other sources like Notion documents. 
+  (Feedback welcome—just open an issue!)
 
 ## v0.0.1
 

lib/parameterized_test.ex

@@ -1,3 +1,6 @@
+NimbleCSV.define(ParameterizedTest.TsvParser, separator: "\t", escape: "\"")
+NimbleCSV.define(ParameterizedTest.CsvParser, separator: ",", escape: "\"")
+
 defmodule ParameterizedTest do
   @moduledoc ~S"""
   A utility for defining eminently readable parameterized (or example-based) tests.
@@ -72,9 +75,31 @@ defmodule ParameterizedTest do
 
     escaped_examples =
       case examples do
-        str when is_binary(str) -> str |> parse_examples(context) |> Macro.escape()
-        list when is_list(list) -> list |> parse_examples(context) |> Macro.escape()
-        already_escaped when is_tuple(already_escaped) -> already_escaped
+        str when is_binary(str) ->
+          file_extension =
+            str
+            |> Path.extname()
+            |> String.downcase()
+
+          case file_extension do
+            ext when ext in [".md", ".markdown", ".csv"] ->
+              str
+              |> parse_file_path_examples(context)
+              |> Macro.escape()
+
+            _ ->
+              str
+              |> parse_examples(context)
+              |> Macro.escape()
+          end
+
+        list when is_list(list) ->
+          list
+          |> parse_examples(context)
+          |> Macro.escape()
+
+        already_escaped when is_tuple(already_escaped) ->
+          already_escaped
       end
 
     max_describe_length_to_fit_on_one_line = 82
@@ -104,58 +129,10 @@ defmodule ParameterizedTest do
   def parse_examples(table, context \\ [])
 
   def parse_examples(table, context) when is_binary(table) do
-    rows =
-      table
-      |> String.split("\n", trim: true)
-      |> Enum.map(&String.trim/1)
-
-    case rows do
-      [header | rows] ->
-        headers =
-          header
-          |> split_cells()
-          |> Enum.map(&String.to_atom/1)
-
-        rows
-        |> Enum.reject(&separator_row?/1)
-        |> Enum.map(fn row ->
-          cells =
-            row
-            |> split_cells()
-            |> Enum.map(fn cell ->
-              try do
-                case Code.eval_string(cell) do
-                  {val, []} -> val
-                  _ -> raise "Failed to evaluate example cell `#{cell}` in row `#{row}`"
-                end
-              rescue
-                e ->
-                  reraise "Failed to evaluate example cell `#{cell}` in row `#{row}`. #{inspect(e)}", __STACKTRACE__
-              end
-            end)
-
-          if length(cells) != length(headers) do
-            raise """
-            The number of cells in each row must exactly match the
-            number of headers on your example table.
-
-            Problem row#{file_meta(context)}:
-            #{row}
-
-            Expected headers:
-            #{inspect(headers)}
-            """
-          end
-
-          headers
-          |> Enum.zip(cells)
-          |> Map.new()
-        end)
-        |> Enum.reject(&(&1 == %{}))
-
-      [] ->
-        []
-    end
+    table
+    |> String.split("\n", trim: true)
+    |> Enum.map(&String.trim/1)
+    |> parse_md_rows(context)
   end
 
   # This function head handles a list of already-parsed examples, like:
@@ -166,6 +143,14 @@ defmodule ParameterizedTest do
   #            ], %{int_1: int_1, int_2: int_2} do
   def parse_examples(table, context) when is_list(table) do
     {evaled_table, _, _} = Code.eval_quoted_with_env(table, [], __ENV__)
+
+    case evaled_table do
+      str when is_binary(str) -> parse_file_path_examples(str, context)
+      list when is_list(list) -> parse_hand_rolled_table(list, context)
+    end
+  end
+
+  defp parse_hand_rolled_table(evaled_table, context) do
     parsed_table = Enum.map(evaled_table, &Map.new/1)
 
     keys = MapSet.new(parsed_table, &Map.keys/1)
@@ -182,6 +167,100 @@ defmodule ParameterizedTest do
     parsed_table
   end
 
+  defp parse_file_path_examples(path, context) do
+    file = File.read!(path)
+
+    case path |> Path.extname() |> String.downcase() do
+      md when md in [".md", ".markdown"] -> parse_examples(file, context)
+      ".csv" -> parse_csv_file(file, context)
+      ".tsv" -> parse_tsv_file(file, context)
+      _ -> raise "Unsupported file extension for parameterized tests #{path} #{file_meta(context)}"
+    end
+  end
+
+  defp parse_csv_file(file, context) do
+    file
+    |> ParameterizedTest.CsvParser.parse_string(skip_headers: false)
+    |> parse_csv_rows(context)
+  end
+
+  defp parse_tsv_file(file, context) do
+    file
+    |> ParameterizedTest.TsvParser.parse_string()
+    |> Enum.map(&String.trim/1)
+    |> parse_csv_rows(context)
+  end
+
+  defp parse_md_rows(rows, context)
+  defp parse_md_rows([], _context), do: []
+
+  defp parse_md_rows([header | rows], context) do
+    headers =
+      header
+      |> split_cells()
+      |> Enum.map(&String.to_atom/1)
+
+    rows
+    |> Enum.reject(&separator_row?/1)
+    |> Enum.map(fn row ->
+      cells =
+        row
+        |> split_cells()
+        |> Enum.map(&eval_cell(&1, row, context))
+
+      check_cell_count(cells, headers, row, context)
+
+      headers
+      |> Enum.zip(cells)
+      |> Map.new()
+    end)
+    |> Enum.reject(&(&1 == %{}))
+  end
+
+  defp parse_csv_rows(rows, context)
+  defp parse_csv_rows([], _context), do: []
+
+  defp parse_csv_rows([header | rows], context) do
+    headers = Enum.map(header, &String.to_atom/1)
+
+    rows
+    |> Enum.map(fn row ->
+      cells = Enum.map(row, &eval_cell(&1, row, context))
+
+      check_cell_count(cells, headers, row, context)
+
+      headers
+      |> Enum.zip(cells)
+      |> Map.new()
+    end)
+    |> Enum.reject(&(&1 == %{}))
+  end
+
+  defp eval_cell(cell, row, _context) do
+    case Code.eval_string(cell) do
+      {val, []} -> val
+      _ -> raise "Failed to evaluate example cell `#{cell}` in row `#{row}`}"
+    end
+  rescue
+    e ->
+      reraise "Failed to evaluate example cell `#{cell}` in row `#{row}`. #{inspect(e)}", __STACKTRACE__
+  end
+
+  defp check_cell_count(cells, headers, row, context) do
+    if length(cells) != length(headers) do
+      raise """
+      The number of cells in each row must exactly match the
+      number of headers on your example table.
+
+      Problem row#{file_meta(context)}:
+      #{row}
+
+      Expected headers:
+      #{inspect(headers)}
+      """
+    end
+  end
+
   defp split_cells(row) do
     row
     |> String.split("|", trim: true)

mix.exs

@@ -77,6 +77,7 @@ defmodule ParameterizedTest.MixProject do
   defp deps do
     List.flatten(
       [
+        {:nimble_csv, "~> 1.1"},
         {:ex_doc, ">= 0.0.0", only: :dev, runtime: false},
 
         # Code quality

mix.lock

@@ -11,6 +11,7 @@
   "makeup": {:hex, :makeup, "1.1.2", "9ba8837913bdf757787e71c1581c21f9d2455f4dd04cfca785c70bbfff1a76a3", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cce1566b81fbcbd21eca8ffe808f33b221f9eee2cbc7a1706fc3da9ff18e6cac"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.16.2", "627e84b8e8bf22e60a2579dad15067c755531fea049ae26ef1020cad58fe9578", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "41193978704763f6bbe6cc2758b84909e62984c7752b3784bd3c218bb341706b"},
   "makeup_erlang": {:hex, :makeup_erlang, "1.0.0", "6f0eff9c9c489f26b69b61440bf1b238d95badae49adac77973cbacae87e3c2e", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "ea7a9307de9d1548d2a72d299058d1fd2339e3d398560a0e46c27dab4891e4d2"},
+  "nimble_csv": {:hex, :nimble_csv, "1.2.0", "4e26385d260c61eba9d4412c71cea34421f296d5353f914afe3f2e71cce97722", [:mix], [], "hexpm", "d0628117fcc2148178b034044c55359b26966c6eaa8e2ce15777be3bbc91b12a"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.4.0", "51f9b613ea62cfa97b25ccc2c1b4216e81df970acd8e16e8d1bdc58fef21370d", [:mix], [], "hexpm", "9c565862810fb383e9838c1dd2d7d2c437b3d13b267414ba6af33e50d2d1cf28"},
   "styler": {:hex, :styler, "0.11.9", "2595393b94e660cd6e8b582876337cc50ff047d184ccbed42fdad2bfd5d78af5", [:mix], [], "hexpm", "8b7806ba1fdc94d0a75127c56875f91db89b75117fcc67572661010c13e1f259"},
 }

test/fixtures/params.csv

@@ -0,0 +1,3 @@
+coupon,gets_free_shipping?
+,false
+"""FREE_SHIP""",true

test/fixtures/params.md

@@ -0,0 +1,6 @@
+| spending_by_category          | coupon      | gets_free_shipping? |
+|-------------------------------|-------------|---------------------|
+| %{shoes: 19_99, pants: 29_99} |             | false               |
+| %{shoes: 59_99, pants: 49_99} |             | true                |
+| %{socks: 10_99}               |             | true                |
+| %{shoes: 19_99}               | "FREE_SHIP" | true                |

test/fixtures/params.tsv

@@ -0,0 +1,3 @@
+coupon	gets_free_shipping?
+	false
+"""FREE_SHIP"""	true

test/parameterized_test_test.exs

@@ -42,6 +42,36 @@ defmodule ParameterizedTestTest do
       free_shipping? = shipping_cost == 0
       assert free_shipping? == gets_free_shipping?
     end
+
+    param_test "supports Markdown files as input",
+               "test/fixtures/params.md",
+               %{
+                 spending_by_category: spending_by_category,
+                 coupon: coupon,
+                 gets_free_shipping?: gets_free_shipping?
+               } do
+      shipping_cost = ExampleShippingCalculator.calculate_shipping(spending_by_category, coupon)
+      free_shipping? = shipping_cost == 0
+      assert free_shipping? == gets_free_shipping?
+    end
+
+    param_test "supports CSV files as input",
+               "test/fixtures/params.csv",
+               %{
+                 coupon: coupon,
+                 gets_free_shipping?: gets_free_shipping?
+               } do
+      assert (coupon == "FREE_SHIP" and gets_free_shipping?) or (is_nil(coupon) and not gets_free_shipping?)
+    end
+
+    param_test "supports TSV files as input",
+               "test/fixtures/params.csv",
+               %{
+                 coupon: coupon,
+                 gets_free_shipping?: gets_free_shipping?
+               } do
+      assert (coupon == "FREE_SHIP" and gets_free_shipping?) or (is_nil(coupon) and not gets_free_shipping?)
+    end
   end
 
   defmodule ExampleAccounts do