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测量快速执行的测试代码

对于执行速度太快以至于 MATLAB® 不能准确测量的性能测试，将通过假设失败将其滤除。使用 keepMeasuring 方法，测试框架可以通过自动确定代码迭代次数并测量平均性能来显著加快代码测量速度。

在您的当前工作文件夹中创建一个基于类的测试，PreallocationTest.m，用于对不同的预分配方法进行比较。由于测试方法中包括鉴定，因此可以使用 startMeasuring 和 stopMeasuring 方法来定义要测量的代码的边界。

classdef PreallocationTest < matlab.perftest.TestCase
    methods(Test)
        function testOnes(testCase)
            testCase.startMeasuring
            x = ones(1,1e5);
            testCase.stopMeasuring
            testCase.verifyEqual(size(x),[1 1e5])
        end
        
        function testIndexingWithVariable(testCase)
            import matlab.unittest.constraints.IsSameSetAs
            testCase.startMeasuring
            id = 1:1e5;
            x(id) = 1;
            testCase.stopMeasuring
            testCase.verifyThat(x,IsSameSetAs(1))
        end
        
        function testIndexingOnLHS(testCase)
            import matlab.unittest.constraints.EveryElementOf
            import matlab.unittest.constraints.IsEqualTo
            testCase.startMeasuring
            x(1:1e5) = 1;
            testCase.stopMeasuring
            testCase.verifyThat(EveryElementOf(x),IsEqualTo(1))
        end
        
        function testForLoop(testCase)
            testCase.startMeasuring
            for i=1:1e5
                x(i) = 1;
            end
            testCase.stopMeasuring
            testCase.verifyNumElements(x,1e5)
        end
    end
end

运行 PreallocationTest 作为性能测试。滤除两个测试，因为测量结果太接近框架的精度。

results = runperf('PreallocationTest');
Running PreallocationTest
........
================================================================================
PreallocationTest/testOnes was filtered.
    Test Diagnostic: The MeasuredTime should not be too close to the precision of the framework.
Details
================================================================================
.. .......... ....
================================================================================
PreallocationTest/testIndexingOnLHS was filtered.
    Test Diagnostic: The MeasuredTime should not be too close to the precision of the framework.
Details
================================================================================
...... ..
Done PreallocationTest
__________

Failure Summary:

     Name                                 Failed  Incomplete  Reason(s)
    ==================================================================================
     PreallocationTest/testOnes                       X       Filtered by assumption.
    ----------------------------------------------------------------------------------
     PreallocationTest/testIndexingOnLHS              X       Filtered by assumption.

要指示框架自动遍历已测量的代码并计算测量结果平均值，请修改 PreallocationTest 以使用 keepMeasuring-while 循环，而不是使用 startMeasuring 和 stopMeasuring。

classdef PreallocationTest < matlab.perftest.TestCase
    methods(Test)
        function testOnes(testCase)
            while(testCase.keepMeasuring)
                x = ones(1,1e5);
            end
            testCase.verifyEqual(size(x),[1 1e5])
        end
        
        function testIndexingWithVariable(testCase)
            import matlab.unittest.constraints.IsSameSetAs
            while(testCase.keepMeasuring)
                id = 1:1e5;
                x(id) = 1;
            end
            testCase.verifyThat(x,IsSameSetAs(1))
        end
        
        function testIndexingOnLHS(testCase)
            import matlab.unittest.constraints.EveryElementOf
            import matlab.unittest.constraints.IsEqualTo
            while(testCase.keepMeasuring)
                x(1:1e5) = 1;
            end
            testCase.verifyThat(EveryElementOf(x),IsEqualTo(1))
        end
        
        function testForLoop(testCase)
            while(testCase.keepMeasuring)
                for i=1:1e5
                    x(i) = 1;
                end
            end
            testCase.verifyNumElements(x,1e5)
        end
    end
end

重新运行测试。所有测试全部完成。

results = runperf('PreallocationTest');
Running PreallocationTest
.......... .......... .......... ..
Done PreallocationTest
__________

查看结果。

sampleSummary(results)
ans =

  4×7 table

                       Name                       SampleSize       Mean       StandardDeviation       Min          Median         Max    
    __________________________________________    __________    __________    _________________    __________    __________    __________

    PreallocationTest/testOnes                        4         3.0804e-05       1.8337e-07        3.0577e-05    3.0843e-05    3.0953e-05
    PreallocationTest/testIndexingWithVariable        4         0.00044536       1.7788e-05        0.00042912    0.00044396    0.00046441
    PreallocationTest/testIndexingOnLHS               4         5.6352e-05       1.8863e-06        5.5108e-05    5.5598e-05    5.9102e-05
    PreallocationTest/testForLoop                     4          0.0097656       0.00018202         0.0096181     0.0097065      0.010031

另请参阅

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