Reimplement given as provided and deprecate

The behavior is slightly different now.
Nested example blocks aren't allowed in `provided`.
The block produces one example, not multiple.

src/spectator/dsl/concise.cr

@@ -0,0 +1,41 @@
+require "./examples"
+require "./groups"
+require "./memoize"
+
+module Spectator::DSL
+  # DSL methods and macros for shorter syntax.
+  module Concise
+    # Defines an example and input values in a shorter syntax.
+    # The only arguments given to this macro are one or more assignments.
+    # The names in the assigments will be available in the example code.
+    #
+    # If the code block is omitted, then the example is skipped (marked as not implemented).
+    #
+    # Tags and metadata cannot be used with this macro.
+    #
+    # ```
+    # given x = 42 do
+    #   expect(x).to eq(42)
+    # end
+    # ```
+    macro provided(*assignments, &block)
+      class Given%given < {{@type.id}}
+        {% for assignment in assignments %}
+          let({{assignment.target}}) { {{assignment.value}} }
+        {% end %}
+
+        {% if block %}
+          example {{block}}
+        {% else %}
+          example {{assignments.splat.stringify}}
+        {% end %}
+      end
+    end
+
+    # :ditto:
+    @[Deprecated("Use `provided` instead.")]
+    macro given(*assignments, &block)
+      provided({{assignments.splat}}) {{block}}
+    end
+  end
+end

src/spectator/dsl/groups.cr

@@ -116,6 +116,6 @@ module Spectator::DSL
 
     define_example_group :xcontext, skip: "Temporarily skipped with xcontext"
 
-    # TODO: sample, random_sample, and given
+    # TODO: sample, random_sample
   end
 end

src/spectator/test_context.cr

@@ -8,6 +8,7 @@ require "./tags"
 # This type is intentionally outside the `Spectator` module.
 # The reason for this is to prevent name collision when using the DSL to define a spec.
 class SpectatorTestContext < SpectatorContext
+  include ::Spectator::DSL::Concise
   include ::Spectator::DSL::Examples
   include ::Spectator::DSL::Expectations
   include ::Spectator::DSL::Groups