Create example harness

src/spectator/internals/harness.cr

@@ -0,0 +1,45 @@
+module Spectator::Internals
+  # Helper class that acts as a gateway between example code and the test framework.
+  # Every example run must be called with `#run`.
+  # This sets up the harness so that the example code can use it.
+  # The test framework does the following:
+  # ```
+  # result = Harness.run(example)
+  # # Do something with the result.
+  # ```
+  # Then from the example code, the harness can be accessed via `#current` like so:
+  # ```
+  # harness = ::Spectator::Internals::Harness.current
+  # # Do something with the harness.
+  # ```
+  # Of course, the end-user shouldn't see this or work directly with the harness.
+  # Instead, methods the user calls can access it.
+  # For instance, an expectation reporting a result.
+  class Harness
+    # Retrieves the harness for the current running example.
+    class_getter! current : self
+
+    # Wraps an example with a harness and runs the example.
+    # The `#current` harness will be set
+    # prior to running the example, and reset after.
+    # The `example` argument will be the example to run.
+    # The result returned from `Example#run` will be returned.
+    def self.run(example : Example) : Result
+      @@current = new(example)
+      result = example.run
+      @@current = nil
+      result
+    end
+
+    # Retrieves the current running example.
+    getter example : Example
+
+    # Provides access to the expectation reporter.
+    getter reporter = Expectations::ExpectationReporter.new
+
+    # Creates a new harness.
+    # The example the harness is for should be passed in.
+    private def initialize(@example)
+    end
+  end
+end