Lazy message/diff creation for assertion in `test/assert.rb`

Include the following changes too:

- Extract part of logic with block to a method
- Use `var ||= ...` instead of `var = ... unless var`
- Unify using parentheses for `t_print`
- Change methods order

test/assert.rb

@@ -79,8 +79,8 @@ def assert_true(ret, msg = nil, diff = nil)
   if $mrbtest_assert
     $mrbtest_assert_idx += 1
     unless ret
-      msg = "Expected #{ret.inspect} to be true" unless msg
-      diff = assertion_diff(true, ret)  unless diff
+      msg ||= "Expected #{ret.inspect} to be true"
+      diff ||= assertion_diff(true, ret)
       $mrbtest_assert.push([$mrbtest_assert_idx, msg, diff])
     end
   end
@@ -96,74 +96,88 @@ def assert_false(ret, msg = nil, diff = nil)
   !ret
 end
 
-def assert_equal(arg1, arg2 = nil, arg3 = nil)
-  if block_given?
-    exp, act, msg = arg1, yield, arg2
-  else
-    exp, act, msg = arg1, arg2, arg3
-  end
-
-  msg = "Expected to be equal" unless msg
+def assert_equal(exp, act_or_msg = nil, msg = nil, &block)
+  ret, exp, act, msg = _eval_assertion(:==, exp, act_or_msg, msg, block)
+  unless ret
+    msg ||= "Expected to be equal"
     diff = assertion_diff(exp, act)
-  assert_true(exp == act, msg, diff)
-end
-
-def assert_not_equal(arg1, arg2 = nil, arg3 = nil)
-  if block_given?
-    exp, act, msg = arg1, yield, arg2
-  else
-    exp, act, msg = arg1, arg2, arg3
   end
-
-  msg = "Expected to be not equal" unless msg
-  diff = assertion_diff(exp, act)
-  assert_false(exp == act, msg, diff)
+  assert_true(ret, msg, diff)
 end
 
-def assert_same(arg1, arg2 = nil, arg3 = nil)
-  if block_given?
-    exp, act, msg = arg1, yield, arg2
-  else
-    exp, act, msg = arg1, arg2, arg3
+def assert_not_equal(exp, act_or_msg = nil, msg = nil, &block)
+  ret, exp, act, msg = _eval_assertion(:==, exp, act_or_msg, msg, block)
+  if ret
+    msg ||= "Expected to be not equal"
+    diff = assertion_diff(exp, act)
   end
+  assert_true(!ret, msg, diff)
+end
 
+def assert_same(exp, act_or_msg = nil, msg = nil, &block)
+  ret, exp, act, msg = _eval_assertion(:equal?, exp, act_or_msg, msg, block)
+  unless ret
     msg ||= "Expected #{act.inspect} to be the same object as #{exp.inspect}"
     diff = "    Expected: #{exp.inspect} (class=#{exp.class}, oid=#{exp.__id__})\n" +
            "      Actual: #{act.inspect} (class=#{act.class}, oid=#{act.__id__})"
-  assert_true(exp.equal?(act), msg, diff)
-end
-
-def assert_not_same(arg1, arg2 = nil, arg3 = nil)
-  if block_given?
-    exp, act, msg = arg1, yield, arg2
-  else
-    exp, act, msg = arg1, arg2, arg3
   end
+  assert_true(ret, msg, diff)
+end
 
+def assert_not_same(exp, act_or_msg = nil, msg = nil, &block)
+  ret, exp, act, msg = _eval_assertion(:equal?, exp, act_or_msg, msg, block)
+  if ret
     msg ||= "Expected #{act.inspect} to not be the same object as #{exp.inspect}"
     diff = "    Expected: #{exp.inspect} (class=#{exp.class}, oid=#{exp.__id__})\n" +
            "      Actual: #{act.inspect} (class=#{act.class}, oid=#{act.__id__})"
-  assert_false(exp.equal?(act), msg, diff)
+  end
+  assert_true(!ret, msg, diff)
 end
 
 def assert_nil(obj, msg = nil)
-  msg = "Expected #{obj.inspect} to be nil" unless msg
+  unless ret = obj.nil?
+    msg ||= "Expected #{obj.inspect} to be nil"
     diff = assertion_diff(nil, obj)
-  assert_true(obj.nil?, msg, diff)
+  end
+  assert_true(ret, msg, diff)
 end
 
 def assert_include(collection, obj, msg = nil)
-  msg = "Expected #{collection.inspect} to include #{obj.inspect}" unless msg
+  unless ret = collection.include?(obj)
+    msg ||= "Expected #{collection.inspect} to include #{obj.inspect}"
     diff = "    Collection: #{collection.inspect}\n" +
            "        Object: #{obj.inspect}"
-  assert_true(collection.include?(obj), msg, diff)
+  end
+  assert_true(ret, msg, diff)
 end
 
 def assert_not_include(collection, obj, msg = nil)
-  msg = "Expected #{collection.inspect} to not include #{obj.inspect}" unless msg
+  if ret = collection.include?(obj)
+    msg ||= "Expected #{collection.inspect} to not include #{obj.inspect}"
     diff = "    Collection: #{collection.inspect}\n" +
            "        Object: #{obj.inspect}"
-  assert_false(collection.include?(obj), msg, diff)
+  end
+  assert_true(!ret, msg, diff)
+end
+
+##
+# Fails unless +obj+ is a kind of +cls+.
+def assert_kind_of(cls, obj, msg = nil)
+  unless ret = obj.kind_of?(cls)
+    msg ||= "Expected #{obj.inspect} to be a kind of #{cls}, not #{obj.class}"
+    diff = assertion_diff(cls, obj.class)
+  end
+  assert_true(ret, msg, diff)
+end
+
+##
+# Fails unless +exp+ is equal to +act+ in terms of a Float
+def assert_float(exp, act, msg = nil)
+  unless ret = check_float(exp, act)
+    msg ||= "Float #{exp} expected to be equal to float #{act}"
+    diff = assertion_diff(exp, act)
+  end
+  assert_true(ret, msg, diff)
 end
 
 def assert_raise(*exc)
@@ -197,22 +211,6 @@ def assert_nothing_raised(msg = nil)
   end
 end
 
-##
-# Fails unless +obj+ is a kind of +cls+.
-def assert_kind_of(cls, obj, msg = nil)
-  msg = "Expected #{obj.inspect} to be a kind of #{cls}, not #{obj.class}" unless msg
-  diff = assertion_diff(cls, obj.class)
-  assert_true(obj.kind_of?(cls), msg, diff)
-end
-
-##
-# Fails unless +exp+ is equal to +act+ in terms of a Float
-def assert_float(exp, act, msg = nil)
-  msg = "Float #{exp} expected to be equal to float #{act}" unless msg
-  diff = assertion_diff(exp, act)
-  assert_true check_float(exp, act), msg, diff
-end
-
 ##
 # Report the test result and print all assertions
 # which were reported broken.
@@ -220,7 +218,7 @@ def report()
   t_print("\n")
 
   $asserts.each do |msg|
-    t_print "#{msg}\n"
+    t_print("#{msg}\n")
   end
 
   $total_test = $ok_test+$ko_test+$kill_test
@@ -249,6 +247,15 @@ def check_float(a, b)
   end
 end
 
+def _eval_assertion(meth, exp, act_or_msg, msg, block)
+  if block
+    exp, act, msg = exp, block.call, act_or_msg
+  else
+    exp, act, msg = exp, act_or_msg, msg
+  end
+  return exp.__send__(meth, act), exp, act, msg
+end
+
 ##
 # Skip the test
 class MRubyTestSkip < NotImplementedError