Introduce Rule Support

kevin-johnson-shopify · kevin-johnson-shopify · commit e4a449ad7fcc · 2020-07-22T06:57:30.000-04:00
diff --git a/apps/ex_cucumber/lib/ex_cucumber/gherkin/traverser/background_traverser.ex b/apps/ex_cucumber/lib/ex_cucumber/gherkin/traverser/background_traverser.ex
@@ -10,17 +10,24 @@ defmodule ExCucumber.Gherkin.Traverser.Background do
   }
 
   def run(%Background{} = b, acc, parse_tree) do
-    acc = Ctx.extra(acc, background_meta(b))
+    acc = Ctx.extra(acc, background_meta(b, acc))
 
     b.steps
     |> Enum.reduce(acc, fn
       %Step{} = step, a -> MainTraverser.run(step, a, parse_tree)
     end)
   end
 
-  defp background_meta(background) do
+  defp background_meta(background, acc) do
+    background_key =
+      if Map.has_key?(acc.extra, :rule) do
+        :background_rule
+      else
+        :background
+      end
+
     %{
-      background: %{
+      background_key => %{
         title: background.name,
         location: Map.from_struct(background.location),
         keyword: background.keyword
diff --git a/apps/ex_cucumber/lib/ex_cucumber/gherkin/traverser/rule_traverser.ex b/apps/ex_cucumber/lib/ex_cucumber/gherkin/traverser/rule_traverser.ex
@@ -0,0 +1,39 @@
+defmodule ExCucumber.Gherkin.Traverser.Rule do
+  @moduledoc false
+
+  alias ExCucumber.Gherkin.Traverser.Ctx
+  alias ExCucumber.Gherkin.Traverser, as: MainTraverser
+
+  alias ExGherkin.AstNdjson.Background
+
+  def run(%ExGherkin.AstNdjson.Rule{} = r, acc, parse_tree) do
+    {background, children} = background(r.children)
+
+    acc = Ctx.extra(acc, rule_meta(r))
+
+    children
+    |> Enum.each(fn child ->
+      acc = MainTraverser.run(background, acc, parse_tree)
+
+      child
+      |> case do
+        %{scenario: scenario} -> MainTraverser.run(scenario, acc, parse_tree)
+      end
+    end)
+  end
+
+  defp background([]), do: {nil, []}
+  defp background([%{background: b = %Background{}}]), do: {b, []}
+  defp background([%{background: b = %Background{}} | tl]), do: {b, tl}
+  defp background(ls), do: {nil, ls}
+
+  defp rule_meta(rule) do
+    %{
+      rule: %{
+        title: rule.name,
+        location: Map.from_struct(rule.location),
+        keyword: rule.keyword
+      }
+    }
+  end
+end
diff --git a/apps/ex_cucumber/lib/ex_cucumber/gherkin/traverser/traverser.ex b/apps/ex_cucumber/lib/ex_cucumber/gherkin/traverser/traverser.ex
@@ -3,6 +3,7 @@ defmodule ExCucumber.Gherkin.Traverser do
   alias __MODULE__.Ctx
   alias __MODULE__.Feature, as: FeatureTraverser
   alias __MODULE__.Background, as: BackgroundTraverser
+  alias __MODULE__.Rule, as: RuleTraverser
   alias __MODULE__.Scenario, as: ScenarioTraverser
   alias __MODULE__.Step, as: StepTraverser
 
@@ -20,6 +21,9 @@ defmodule ExCucumber.Gherkin.Traverser do
   def run(%ExGherkin.AstNdjson.Background{} = f, acc, parse_tree),
     do: BackgroundTraverser.run(f, acc, parse_tree)
 
+  def run(%ExGherkin.AstNdjson.Rule{} = f, acc, parse_tree),
+    do: RuleTraverser.run(f, acc, parse_tree)
+
   def run(%ExGherkin.AstNdjson.Scenario{token: _} = f, acc, parse_tree),
     do: ScenarioTraverser.run(f, acc, parse_tree)
 
diff --git a/apps/ex_cucumber/test/ex_cucumber_test.exs b/apps/ex_cucumber/test/ex_cucumber_test.exs
@@ -30,7 +30,9 @@ defmodule ExCucumberTest do
     Params.Canonical => "#{@support_module_dir}/params/canonical.ex",
     Params.Custom => "#{@support_module_dir}/params/custom.ex",
     BookStoreFeature.DemonstrateBackgroundUsage =>
-      "#{@support_module_dir}/book_store_feature/demonstrate_background_usage.ex"
+      "#{@support_module_dir}/book_store_feature/demonstrate_background_usage.ex",
+    RuleFeature.DemonstrateRuleUsage =>
+      "#{@support_module_dir}/rule_feature/demonstrate_rule_usage.ex"
   }
 
   setup_all do
@@ -120,6 +122,13 @@ defmodule ExCucumberTest do
         recompile(ctx)
       end)
     end
+
+    @tag test_module: RuleFeature.DemonstrateRuleUsage
+    test "Handles Rule", ctx do
+      refute_raise(fn ->
+        recompile(ctx)
+      end)
+    end
   end
 
   def reset_env_switch(ctx) do
diff --git a/apps/ex_cucumber/test/support/features/rule.feature b/apps/ex_cucumber/test/support/features/rule.feature
@@ -0,0 +1,25 @@
+Feature: Gherkin 6 syntax
+
+  Background:
+    Given there is a monster with 2 hitpoints
+
+  Scenario: Battle
+    When I attack it
+    Then the monster should be alive
+    When I attack it
+    Then it should die
+
+  Rule: Battle with preemptive attack
+    Background:
+      Given I attack the monster and do 1 points damage
+
+    Example: battle
+      When I attack it
+      Then it should die
+
+  Rule: Battle with preemptive critical attack
+    Background:
+      Given I attack the monster and do 2 points damage
+
+    Example: battle
+      Then it should die
diff --git a/apps/ex_cucumber/test/support/modules/rule_feature/demonstrate_rule_usage.ex b/apps/ex_cucumber/test/support/modules/rule_feature/demonstrate_rule_usage.ex
@@ -0,0 +1,43 @@
+defmodule Support.RuleFeature.DemonstrateRuleUsage do
+  use ExCucumber
+  @feature "rule.feature"
+
+  defmodule Monster do
+    defstruct hitpoints: 0,
+              alive?: false
+
+    def new(hitpoints), do: __MODULE__ |> struct(%{hitpoints: hitpoints}) |> check_alive
+
+    def take_hit(%__MODULE__{} = m, damage \\ 1),
+      do: %{m | hitpoints: m.hitpoints - damage} |> check_alive
+
+    defp check_alive(%__MODULE__{} = m), do: %{m | alive?: m.hitpoints > 0}
+  end
+
+  # Main Background
+  Given._ "there is a monster with {int} hitpoints", args do
+    {
+      :ok,
+      %{
+        monster: Monster.new(Keyword.fetch!(args.params, :int))
+      }
+    }
+  end
+
+  # Scenario: Battle
+  When._ "I attack it", args do
+    {:ok, %{monster: Monster.take_hit(args.state.monster)}}
+  end
+
+  Then._ "the monster should be alive", args do
+    assert args.state.monster.alive?
+  end
+
+  Then._ "it should die", args do
+    refute args.state.monster.alive?
+  end
+
+  Given._ "I attack the monster and do {int} points damage", args do
+    {:ok, %{monster: Monster.take_hit(args.state.monster, Keyword.fetch!(args.params, :int))}}
+  end
+end
