(maint) Update Minitest capitalization

Minitest v5.19.0, released today, includes a commit[1] that only calls
its compatibility layer when using an environment variable
("MT_COMPAT").

This means that calling "MiniTest" (with a capital "T") instead of
"Minitest" (with all lowercase "T"s) no longer works.

This commit replaces all instances of "MiniTest" with "Minitest."

[1] minitest/minitest@a2c6c18

acceptance/lib/helpers/test_helper.rb

@@ -59,7 +59,7 @@ def create_local_file_from_fixture(fixture, local_path, filename, perms = nil)
 #      assert_equal expected, user
 #    end
 #
-# Absorbs any MiniTest::Assertion from a failing test assertion in the block.
+# Absorbs any Minitest::Assertion from a failing test assertion in the block.
 # This implies that the intermittent failure is caught and the suite will not
 # go red for this failure. Intended to be used with the Jenkins Build Failure
 # Analyzer (or similar), to detect these failures without failing the build.
@@ -69,7 +69,7 @@ def fails_intermittently(issue_link, args = {})
   raise ArgumentError, "provide a Jira ticket link" unless issue_link
   raise ArgumentError, "a block is required" unless block_given?
   yield
-rescue MiniTest::Assertion, StandardError, SignalException # we have a test failure!
+rescue Minitest::Assertion, StandardError, SignalException # we have a test failure!
   STDERR.puts "\n\nIntermittent test failure! See: #{issue_link}"
 
   if args.empty?

lib/beaker.rb

@@ -36,6 +36,6 @@ module Beaker
   # Shared methods and helpers
   require 'beaker/shared'
 
-  # MiniTest, for including MiniTest::Assertions
+  # Minitest, for including Minitest::Assertions
   require 'minitest/test'
 end

lib/beaker/test_case.rb

@@ -22,7 +22,7 @@ class TestCase
     include Beaker::DSL
 
     # The Exception raised by Ruby's STDLIB's test framework (Ruby 1.9)
-    TEST_EXCEPTION_CLASS = ::MiniTest::Assertion
+    TEST_EXCEPTION_CLASS = ::Minitest::Assertion
 
     # Necessary for implementing {Beaker::DSL::Helpers#confine}.
     # Assumed to be an array of valid {Beaker::Host} objects for

spec/beaker/dsl/assertions_spec.rb

@@ -79,7 +79,7 @@ class ClassMixedWithDSLAssertions
         expect( result ).to receive( :output ).and_return( output )
 
         expect( subject ).to receive( :result ).at_least( :once ).and_return( result )
-        expect { subject.assert_output expectation }.to raise_error( MiniTest::Assertion )
+        expect { subject.assert_output expectation }.to raise_error( Minitest::Assertion )
       end
     end
   end

spec/beaker/dsl/structure_spec.rb

@@ -197,11 +197,11 @@ class ClassMixedWithDSLStructure
   end
 
   describe '#expect_failure' do
-    it 'passes when a MiniTest assertion is raised' do
+    it 'passes when a Minitest assertion is raised' do
       expect( subject ).to receive( :logger ).and_return( logger )
       expect( logger ).to receive( :notify )
       # We changed this lambda to use the simplest assert possible; using assert_equal
-      # caused an error in minitest 5.9.0 trying to write to the file system.
+      # caused an error in Minitest 5.9.0 trying to write to the file system.
       block = lambda { assert(false, 'this assertion should be caught') }
       expect{ subject.expect_failure 'this is an expected failure', &block }.not_to raise_error
     end
@@ -213,9 +213,9 @@ class ClassMixedWithDSLStructure
       expect{ subject.expect_failure 'this is an expected failure', &block }.not_to raise_error
     end
 
-    it 'fails when a non-Beaker, non-MiniTest assertion is raised' do
-      block = lambda { raise 'not a Beaker or MiniTest error' }
-      expect{ subject.expect_failure 'this has a non-Beaker, non-MiniTest exception', &block }.to raise_error(RuntimeError, /not a Beaker or MiniTest error/)
+    it 'fails when a non-Beaker, non-Minitest assertion is raised' do
+      block = lambda { raise 'not a Beaker or Minitest error' }
+      expect{ subject.expect_failure 'this has a non-Beaker, non-Minitest exception', &block }.to raise_error(RuntimeError, /not a Beaker or Minitest error/)
     end
 
     it 'fails when no assertion is raised' do

spec/beaker/host/mac/group_spec.rb

@@ -52,7 +52,7 @@ class MacGroupTest
       result.stdout = ''
       group_name = 'any_name'
       expect( subject ).to receive( :execute ).and_yield(result)
-      expect { subject.group_get(group_name) }.to raise_error(MiniTest::Assertion, "failed to get group #{group_name}")
+      expect { subject.group_get(group_name) }.to raise_error(Minitest::Assertion, "failed to get group #{group_name}")
     end
 
     it 'parses mac dscacheutil output into /etc/group format correctly' do

spec/beaker/host/mac/user_spec.rb

@@ -63,7 +63,7 @@ class MacUserTest
       result.stdout = ''
       user_name = 'any_name'
       expect( subject ).to receive( :execute ).and_yield(result)
-      expect { subject.user_get(user_name) }.to raise_error(MiniTest::Assertion, "failed to get user #{user_name}")
+      expect { subject.user_get(user_name) }.to raise_error(Minitest::Assertion, "failed to get user #{user_name}")
     end
 
     it 'yields correctly with the result object' do