Implement dry-run mode

README.md

@@ -126,7 +126,7 @@ In no particular order, features that have been implemented and are planned:
     - [ ] Test filtering - by name, context, and tags
     - [X] Fail on no tests
     - [ ] Randomize test order
-    - [ ] Dry run - for validation and checking formatted output
+    - [X] Dry run - for validation and checking formatted output
     - [X] Config block in `spec_helper.cr`
     - [X] Config file - `.spectator`
 - [ ] Reporter and formatting

src/spectator/runner.cr

@@ -42,9 +42,20 @@ module Spectator
     # The formatter is given the example and result information.
     private def run_example(example)
       @config.formatter.start_example(example)
-      Internals::Harness.run(example).tap do |result|
-        @config.formatter.end_example(result)
-      end
+      result = if @config.dry_run? && example.is_a?(RunnableExample)
+                 dry_run_result(example)
+               else
+                 Internals::Harness.run(example)
+               end
+      @config.formatter.end_example(result)
+      result
+    end
+
+    # Creates a fake result for an example.
+    private def dry_run_result(example)
+      expectations = [] of Expectations::Expectation
+      example_expectations = Expectations::ExampleExpectations.new(expectations)
+      SuccessfulResult.new(example, Time::Span.zero, example_expectations)
     end
   end
 end