Add class/2 for conditional checking

Author: sn3p

lib/ex_css_modules/ex_css_modules.ex

@@ -46,6 +46,25 @@ defmodule ExCSSModules do
     |> class_attribute
   end
 
+  @doc """
+  If `value` is truthy, read the class definitions and maps them to a class attribute.
+  When `value` is falsy return nil.
+
+  ## Examples
+    iex> class(%{ "hello" => "world"}, "hello", true)
+    {:safe, ~s(class="world")}
+
+    iex> class(%{ "hello" => "world"}, "hello", false)
+    nil
+  """
+  def class(definition, classes, value) do
+    if value do
+      definition
+      |> class_name(classes)
+      |> class_attribute
+    end
+  end
+
   @doc """
   Returns the class name from the definition map if value is true.
 

lib/ex_css_modules/view.ex

@@ -40,6 +40,7 @@ defmodule ExCSSModules.View do
       def stylesheet, do: ExCSSModules.stylesheet(@stylesheet)
 
       def class(key), do: stylesheet() |> ExCSSModules.class(key)
+      def class(key, value), do: stylesheet() |> ExCSSModules.class(key, value)
 
       def class_name(key) do
         ExCSSModules.class_name(stylesheet(), key)

test/ex_css_modules/ex_css_modules_test.exs

@@ -20,18 +20,32 @@ defmodule ExCSSModulesTest do
   end
 
   describe "class/2" do
-    test "returns a Phoenix.HTML :safe class attribute for an existing classname" do
+    test "returns a class attribute for an existing classname" do
       assert ExCSSModules.class(
         %{"hello" => "world"},
         "hello"
-      ) == {:safe, "class=\"world\""}
+      ) == {:safe, ~s(class="world")}
     end
 
-    test "returns an empty Phoenix.HTML :safe class attribute for a non existing classname" do
+    test "returns an empty class attribute for a non existing classname" do
       assert ExCSSModules.class(
         %{"hello" => "world"},
         "foo"
-      ) == {:safe, "class=\"\""}
+      ) == {:safe, ~s(class="")}
+    end
+  end
+
+  describe "class/3" do
+    test "returns a class attribute for an existing classname when value is true" do
+      assert ExCSSModules.class(
+        %{"hello" => "world"},
+        "hello",
+        true
+      ) == {:safe, ~s(class="world")}
+    end
+
+    test "returns nil for an existing classname when value is false" do
+      assert ExCSSModules.class(%{"hello" => "world"}, "hello", false) == nil
     end
   end
 

test/ex_css_modules/view_test.exs

@@ -66,4 +66,13 @@ defmodule ExCSSModules.ViewTest do
         ExCSSModules.class(@example_stylesheet, "title")
     end
   end
+
+  describe "class/2" do
+    test "calls the class/3 method on ExCSSModules" do
+      assert ViewModuleTest.class("title", true) ==
+        ExCSSModules.class(@example_stylesheet, "title", true)
+      assert ViewModuleTest.class("title", false) ==
+        ExCSSModules.class(@example_stylesheet, "title", false)
+    end
+  end
 end