Nodejs学习笔记——Assert（断言）

Assert - a:actual e:expected m:message o:operator v:value b:block: assert.fail(a, e, m, o); assert(v, m), assert.ok(v, [m]); assert.equal(a, e, [m]); assert.notEqual(a, e, [m]); assert.deepEqual(a, e, [m]); assert.notDeepEqual(a, e, [m]); assert.strictEqual(a, e, [m]); assert.notStrictEqual(a, e, [m]); assert.throws(b, [error], [m]); assert.doesNotThrow(b, [m]); assert.ifError(v)

Throws an exception that displays the values for actual and expected separated by the provided operator.

Note: Always throws an exception and display the message which will be "actual operator expected" if it's omited.

e.g assert.fail(1,1,"Always throws this message","=") and assert.fail(1,1,"","+")

Tests if value is truthy, it is equivalent to assert.equal(true, !!value, message);

Note: If the value isn't a truth-value, it throws and exception and display the message which will be "value == true" if it's omited.

e.g assert(0) and assert.ok(0,"Throws me")

Tests shallow, coercive equality with the equal comparison operator ( == ).

e.g assert.equal(1,2,"They are not equal") and assert.equal(1,1,"would not show me")

Tests shallow, coercive non-equality with the not equal comparison operator ( != ).

Note: 综上，是对比结果为false时抛出异常。

Tests for deep equality.

Note: 采用以下步骤比较，只要一个步骤不匹配就抛出异常：

采用===比较；
比较他们是否是Buffers，如果是则比较长度，接下来每字节每字节比较；
用==比较；
最后如果参数是Object对象，则比较他们的属性长度和属性值

Tests for any deep inequality.

Tests strict equality, as determined by the strict equality operator ( === )

Tests strict non-equality, as determined by the strict not equal operator ( !== )

Expects block to throw an error. error can be constructor, RegExp or validation function.

Validate instanceof using constructor:

assert.throws(
	function() {
		throw new Error("Wrong value");
	},
	Error
);

Validate error message using RegExp:

assert.throws(
	function() {
		throw new Error("Wrong value");
	},
	/value/
);

Custom error validation:

assert.throws(
	function() {
		throw new Error("Wrong value");
	},
	function(err) {
		if ( (err instanceof Error) && /value/.test(err) ) {
			return true;
		}
	},
	"unexpected error"
);

Expects block not to throw an error, see assert.throws for details.

Tests if value is not a false value, throws if it is a true value. Useful when testing the first argument, error in callbacks.

Note: it throws error when the value is a truth-value!