RSpec::Expectations 允许你表达一个样例中对象的预期结果。

1. 内建匹配器

1.1 相等

expect(actual).to eq(expected)  # passes if actual == expected
expect(actual).to eql(expected) # passes if actual.eql?(expected)
expect(actual).not_to eql(not_expected) # passes if not(actual.eql?(expected))

注意：新的 expect 语法不再支持 == 匹配器。

1.2 身份标识

expect(actual).to be(expected)    # passes if actual.equal?(expected)
expect(actual).to equal(expected) # passes if actual.equal?(expected)

1.3 比较

expect(actual).to be >  expected
expect(actual).to be >= expected
expect(actual).to be <= expected
expect(actual).to be <  expected
expect(actual).to be_within(delta).of(expected)

1.4 正则表达式

expect(actual).to match(/expression/)

1.5 类型

expect(actual).to be_an_instance_of(expected) # passes if actual.class == expected
expect(actual).to be_a(expected)              # passes if actual.is_a?(expected)
expect(actual).to be_an(expected)             # an alias for be_a
expect(actual).to be_a_kind_of(expected)      # another alias

1.6 真假

expect(actual).to be_truthy   # passes if actual is truthy (not nil or false)
expect(actual).to be true     # passes if actual == true
expect(actual).to be_falsy    # passes if actual is falsy (nil or false)
expect(actual).to be false    # passes if actual == false
expect(actual).to be_nil      # passes if actual is nil
expect(actual).to_not be_nil  # passes if actual is not nil

1.7 预期错误

expect { ... }.to raise_error
expect { ... }.to raise_error(ErrorClass)
expect { ... }.to raise_error("message")
expect { ... }.to raise_error(ErrorClass, "message")

1.8 预期抛出

expect { ... }.to throw_symbol
expect { ... }.to throw_symbol(:symbol)
expect { ... }.to throw_symbol(:symbol, 'value')

1.9 断言匹配

expect(actual).to be_xxx         # passes if actual.xxx?
expect(actual).to have_xxx(:arg) # passes if actual.has_xxx?(:arg)

1.10 范围（Ruby >= 1.9）

expect(1..10).to cover(3)

1.11 集合

expect(actual).to include(expected)
expect(actual).to start_with(expected)
expect(actual).to end_with(expected)

expect(actual).to contain_exactly(individual, items)
# ...which is the same as:
expect(actual).to match_array(expected_array)

2 should 和 should_not 内建匹配器

2.1 相等

actual.should     eq(expected)  # passes if actual == expected
actual.should     == expected   # passes if actual == expected
actual.should_not eql(expected) # passes if actual.eql?(expected)

注意：我们推荐 eq 匹配器而不是 == 以避免 Ruby 的警告。

2.2 身份标识

actual.should     be(expected)    # passes if actual.equal?(expected)
actual.should_not equal(expected) # passes if actual.equal?(expected)

2.3 比较

actual.should be >  expected
actual.should be >= expected
actual.should be <= expected
actual.should be <  expected
actual.should be_within(delta).of(expected)

2.4 正则表达式

actual.should match(/expression/)
actual.should =~ /expression/

2.5 类型

actual.should     be_an_instance_of(expected)
actual.should_not be_a_kind_of(expected)

2.6 真假

actual.should be_true  # passes if actual is truthy (not nil or false)
actual.should be_false # passes if actual is falsy (nil or false)
actual.should be_nil   # passes if actual is nil

2.7 断言

actual.should     be_xxx         # passes if actual.xxx?
actual.should_not have_xxx(:arg) # passes if actual.has_xxx?(:arg)

2.8 范围（Ruby >= 1.9）

(1..10).should cover(3)

2.9 集合

actual.should include(expected)
actual.should start_with(expected)
actual.should end_with(expected)