**foobar**
**foo
bar**
__foobar__
__foo
bar__

__foo*bar*baz__
__foo_bar_baz__
__foo[bar](baz)__

----------------------------------------------------

[
	["bold", [
		["punctuation", "**"],
		"foobar",
		["punctuation", "**"]
	]],
	["bold", [
		["punctuation", "**"],
		"foo\r\nbar",
		["punctuation", "**"]
	]],
	["bold", [
		["punctuation", "__"],
		"foobar",
		["punctuation", "__"]
	]],
	["bold", [
		["punctuation", "__"],
		"foo\r\nbar",
		["punctuation", "__"]
	]],

	["bold", [
		["punctuation", "__"],
		"foo",
		["italic", [
			["punctuation", "*"],
			"bar",
			["punctuation", "*"]
		]],
		"baz",
		["punctuation", "__"]
	]],
	["bold", [
		["punctuation", "__"],
		"foo",
		["italic", [
			["punctuation", "_"],
			"bar",
			["punctuation", "_"]
		]],
		"baz",
		["punctuation", "__"]
	]],
	["bold", [
		["punctuation", "__"],
		"foo",
		["url", [
			"[bar](baz)"
		]],
		["punctuation", "__"]
	]]
]

----------------------------------------------------

Checks for bold. Also tests for inclusion of italic and url.