Python Code Running Assistance

Save run/debug configuration

Choose this command to save the temporary run/debug configuration 'Solver' - now this configuration becomes permanent. As such, it gets the normal icon.

Edit run/debug configuration

This command is first in the list. Choose Edit configurations, and see the Run/Debug Configurations dialog opens:

Here you can see the Solver configuration and its default settings.

The default configuration options are derived from the predefined Python template. Click the Edit configuration templates link, to preview and modify the patterns.

For example, you want to change the Java interpreter to use a remote or other local interpreter. OK, select the interpreter of your choice in the Java page - then any newly created run/debug configuration of the Java type will use this interpreter.

Under the Python node, you see the only run/debug configuration Solver. It belongs to the Java type, and is created against the pattern Python. It is denoted with the icon of the normal opacity - which corresponds to the permanent run/debug configuration (remember, it became permanent because you've saved it - however, any specially created run/debug configuration also becomes permanent). As an example, create a new run/debug configuration of the Python type for the same Solver script, and call it 'Solver1'.

If you change anything in one of the existing run/debug configurations, then only this particular run/debug configuration will be affected.

Redirect standard input from a text file

You can use the Run/Debug Configuration dialog to automatically submit input values from a text file instead of typing them in the Run tool window.

Create the in.txt file with the following values of a, b, and c:

1
11
1

To enable redirecting, select the Redirect input from checkbox and specify the path to the in.txt file.

Save the Run/Debug configuration and run it. Preview the execution results in the Run tool window.

Selecting a test runner

First, choose the test runner. To do that, click on the main toolbar to open the Settings/Preferences dialog, and under the Tools node, click Python Integrated Tools page. Here is where you will select the default test runner:

In this case, this is Unittests. Apply changes and close the dialog.

Creating a test

To run a test, you have to create it first. IntelliJ IDEA suggests a smart way to stub a test out: click the class name and then press Ctrl+Shift+T, or from the main menu, choose Navigate | Test. If a test exists, you can jump directly to it; if it doesn't, IntelliJ IDEA will create it:

Click the suggested action, and IntelliJ IDEA will show the following dialog:

Click OK, and see the test class opened in the editor:

IntelliJ IDEA has produced a test class for us. However, this is but a stub, and lacks the actual testing functionality. So, we’ll import the class to be tested, and add a test method. The resulting code might be as follows:

import unittest

from Solver import Solver



class MyTestCase(unittest.TestCase):

    def test_negative_discr(self):

        s = Solver()

        self.assertRaises(Exception)

    def test_something(self):

        self.assertEqual(True, False)



if __name__ == '__main__':

    unittest.main()

tip

if you have a project directory structure, you will need to reflect that in the auto-completion of your import statement (from Solver import Solver ).

Running a test

When ready with the testing code, right-click the test class name - the Run node of the context menu shows Unittests run/debug configuration.

Launch it and observe results in the Test Runner tab of the Run tool window:

Breakpoint - what is it?

A breakpoint is a line of the source code, where IntelliJ IDEA will suspend, when this line is reached. IntelliJ IDEA discerns several types of breakpoints, each one denoted with its own icon.

Here we'll use the Python line breakpoints.

Setting breakpoints

This is definitely the easiest part of the process. Just click the gutter on the lines you want to explore - and the breakpoints are there:

Note that each breakpoint is denoted also with a red stripe over the entire line. This color corresponds to a breakpoint that has not yet been reached. Later we'll see how the line at breakpoint changes its color.

By the way, removing breakpoints is same easy - just click the gutter.

Hover your mouse pointer over a breakpoint. IntelliJ IDEA shows a tooltip with the most essential breakpoint information - line number and script address. However, if you want to change breakpoint settings, you have to right-click a breakpoint. Try changing breakpoint settings for your own, and see how the breakpoint icon changes.

Debugging session

So, we are now ready for debugging. Let's start.

First of all, select the same Solver run/debug configuration from the run/debug configurations combobox, and click the Debug icon to the right.

What happens next?

• IntelliJ IDEA starts, and then suspends execution at the first breakpoint.

• The line at breakpoint becomes blue. It means that IntelliJ IDEA has reached the line with the breakpoint, but has not yet executed it.

• Next to the executed lines in the editor, the values of the variables appear.

• The Debug tool window appears. This tool window shows all the important information related to debugging, and allows managing the debugging process.

Refer to the product documentation for details.

Working in the Console tab

Why do we need it at all? For example, you'd like to see the error messages, or perform some calculations not related to the current application... With IntelliJ IDEA this is not a problem.

Click the Console tab to bring it forward, and then, on the toolbar of this tab, click the button :

The Java prompt appears, and the console becomes interactive. Try to execute Java commands in this interactive console:

Note that interactive console provides code completion Ctrl+Space and history (Up/Down arrow keys). Refer to the page for more information.

You can always invoke the debug console by using the command Tools | Open Debug Command Line from the main menu.