Add support for interpolation in context names

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
 - Added ability to cast types using the return value from expect/should statements with a type matcher.
+- Added support for string interpolation in context names/labels.
 
 ### Fixed
 - Fix invalid syntax (unterminated call) when recording calls to stubs with an un-named splat.

spec/features/interpolated_label_spec.cr

@@ -8,7 +8,7 @@ Spectator.describe "Interpolated Label" do
     expect(example.name).to eq("interpolates example labels")
   end
 
-  context "within a \#{bar}" do
+  context "within a #{bar}" do
     let(foo) { "multiple" }
 
     it "interpolates context labels" do |example|

src/spectator/context.cr

@@ -4,6 +4,11 @@
 # 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.
 abstract class SpectatorContext
+  # Evaluates the contents of a block within the scope of the context.
+  def eval
+    with self yield
+  end
+
   # Produces a dummy string to represent the context as a string.
   # This prevents the default behavior, which normally stringifies instance variables.
   # Due to the sheer amount of types Spectator can create

src/spectator/dsl/groups.cr

@@ -137,7 +137,7 @@ module Spectator::DSL
                  what.is_a?(NilLiteral) %}
         {{what}}
       {% elsif what.is_a?(StringInterpolation) %}
-        {% raise "String interpolation isn't supported for example group names" %}
+        {{@type.name}}.new.eval { {{what}} }
       {% else %}
         {{what.stringify}}
       {% end %}