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Figure 2 shows that the test failed because the result of the computation did not match the specified value of 6. In this case, the output from thecomputation was correct but the value specified by the test was incorrect.
When testing using the doctest module, you specify what the result must be for the test to pass.If the test fails to produce a matching result, the output will show that the test failed. For the case of Listing 1 and Listing 2 , if the correct result had been specified, the test would simply have returned to the commandprompt with no other output.
A verbose output could have been specified in Listing 2 to cause the test to return positive results even if there were no failures. You will see howto do that in the next example.
This example will perform a test on a simple function named sum in a module named Py1359_1720_02.py as shown in Listing 3 .
| Listing 3 . Contents of the file named Py1359_1720_02.py. |
|---|
def sum(parA,parB):
return parA + parB |
The test file for this example is shown in Listing 4 .
| Listing 4 . Contents of the test file named Py1359_1720_02.txt. |
|---|
>>>from Py1359_1720_02 import sum>>>sum(2,3)
6 |
This file will actually cause two tests to be performed. The first test is to import the function named sum from the module named Py1359_1720_02 . However, no visible output is expected from this test. Therefore, no output is specified in Listing 4 .
The second test is to call the function named sum (shown in Listing 3 ) passing 2 and 3 as parameters. The test file shows that an incorrect output value of 6 is expected from this test. (As before, an incorrect value was specified to force the test to fail for illustration purposes only.)
The batch file used to execute the test is shown in Listing 5 .
| Listing 5 . Contents of the batch filenamed Py1359_1720_02.bat. |
|---|
echo off
rem set the pathpath=%path%;"C:\Program Files (x86)\Python34"
rem perform the testpython -m doctest -v Py1359_1720_02.txt
pause |
This batch file differs from the one shown in Listing 2 in one respect. The -v switch following doctest in the command causes the output to be more verbose than the output from the previousexample.
The execution of the third (python) command in Listing 5 produced the command line output shown in Figure 3 .
| Figure 3 . Output produced by the test file named Py1359_1720_02.txt. |
|---|
Trying:
from Py1359_1720_02 import sumExpecting nothing
okTrying:
sum(2,3)Expecting:
6**********************************************************************
File "Py1359_1720_02.txt", line 2, in Py1359_1720_02.txtFailed example:
sum(2,3)Expected:
6Got:
5**********************************************************************
1 items had failures:1 of 2 in Py1359_1720_02.txt
2 tests in 1 items.1 passed and 1 failed.
***Test Failed*** 1 failures. |
As mentioned earlier, this output is more verbose than the output shown in Figure 2 . In this more verbose output, tests that pass are shown in addition totests that fail. For example, the test of the import statement is shown as ok .
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