Add f-prefix variants of groups and examples

For instance: `fit` for `it "...", :focus`

src/spectator/dsl/examples.cr

@@ -137,6 +137,12 @@ module Spectator::DSL
 
     define_example :specify
 
+    define_example :fexample, focus: true
+
+    define_example :fit, focus: true
+
+    define_example :fspecify, focus: true
+
     @[Deprecated("Behavior of pending blocks will change in Spectator v0.11.0. Use `skip` instead.")]
     define_pending_example :pending
 

src/spectator/dsl/groups.cr

@@ -181,6 +181,12 @@ module Spectator::DSL
 
     define_example_group :xcontext, skip: "Temporarily skipped with xcontext"
 
+    define_example_group :fexample_group, focus: true
+
+    define_example_group :fdescribe, focus: true
+
+    define_example_group :fcontext, focus: true
+
     # Defines a new iterative example group.
     # This type of group duplicates its contents for each element in *collection*.
     #
@@ -197,6 +203,8 @@ module Spectator::DSL
     # :ditto:
     define_iterative_group :xsample, skip: "Temporarily skipped with xsample"
 
+    define_iterative_group :fsample, focus: true
+
     # Defines a new iterative example group.
     # This type of group duplicates its contents for each element in *collection*.
     # This is the same as `#sample` except that the items are shuffled.
@@ -218,5 +226,10 @@ module Spectator::DSL
     define_iterative_group :xrandom_sample, skip: "Temporarily skipped with xrandom_sample" do |collection|
       collection.to_a.shuffle(::Spectator.random)
     end
+
+    # :ditto:
+    define_iterative_group :frandom_sample, focus: true do |collection|
+      collection.to_a.shuffle(::Spectator.random)
+    end
   end
 end