acronym: Update and exclude new tests

exercises/acronym/.meta/generator/acronym_case.rb

@@ -4,4 +4,19 @@ class AcronymCase < Generator::ExerciseCase
   def workload
     assert_equal(expected,  "Acronym.abbreviate('#{phrase}')")
   end
+
+  def to_s(*args)
+    super unless excluded_tests.include?(test_name)
+  end
+
+  private
+
+  # We exclude these tests because they currently don't fit the purpose
+  # we have for Acronym on the Ruby track.
+  def excluded_tests
+    %w(
+      test_apostrophes
+      test_underscore_emphasis
+    )
+  end
 end

exercises/acronym/acronym_test.rb

@@ -1,7 +1,7 @@
 require 'minitest/autorun'
 require_relative 'acronym'
 
-# Common test data version: 1.5.0 787d24e
+# Common test data version: 1.7.0 cacf1f1
 class AcronymTest < Minitest::Test
   def test_basic
     # skip

lib/generator/test_template.erb

@@ -6,5 +6,5 @@ class <%= exercise_test_classname %> < Minitest::Test
 <%=
   test_cases.map.with_index do |test_case, index|
     test_case.to_s(index.zero?)
-  end.join("\n")
+  end.compact.join("\n")
 %>end