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Oct 14: Using Visual Studio and testing

Learning Objectives

After today's class, you should be able to:

  • Use VS Code to run, debug, and auto-format Python programs.
  • Identify at least three keyboard shortcuts specific to VS Code.
  • Describe how to run pytest in VS Code (from multiple locations).
  • Loop through a string, one character at a time, and build a new string.
  • Apply string methods (isalpha, isspace, split, and splitlines).
  • Break down a problem by writing and calling multiple helper functions.

Announcements

  • Due TODAY
  • Due in one week
  • Mid-semester grades in MyMadison
    • Withdraw deadline is Tue 10/21
  • Practice Quiz will be Tuesday, Oct 21

Lecture: Examples of pytest

[10 min]

VSCode Tutorial

[30 min]

  • Visual Studio Code Setup
    • If you are absent today, complete this tutorial on your own
    • Bring your completed VS Code setup to class on Thursday

Demo

[10 min]

Editing

  • Keyboard shortcuts to know:
    • Command Palette F1
    • Rename Symbol F2
    • Go to Definition F12
  • See also Keyboard Shortcuts

Testing

You can run pytest automatically in VS Code!

  1. Click "Testing" (bottom icon) on the Activity Bar (left sidebar).

  2. Now you can click the run buttons to run pytest at any level.

    • You can also "Debug Test" and "Run Test with Coverage".

Note: Over time, extra folders like __pycache__ and .pytest_cache will be created automatically. These folders are automatically hidden by your .vscode/settings.json file.

Exercise

  1. Set a breakpoint in triangles.py.
  2. Right-click the run button in test_triangles.py.
  3. Click "Debug Test" in the context menu.
  4. Step through the code with the debugger.

Haiku Lab

We will finish this lab on Thursday. Complete the following steps in order:

  1. [10 min] Background, Getting Started
  2. [10 min] Implement remove_symbols
  3. [15 min] Implement check_syllables
  4. [15 min] Implement validate_haiku

Background

Haiku is a form of Japanese poetry. A haiku consists of 3 lines of text. The first line must have 5 syllables. The second line must have 7 syllables. And the third line must, again, have 5 syllables.

Example haiku

An old silent pond
A frog jumps into the pond—
Splash! Silence again.

by Matsuo Basho

Additional haiku examples can be found online. Not all English translations follow the 5-7-5 rule.

Getting Started

Create a folder for today's lab. Download the following files:

Install pysyllables via the terminal: pip install pysyllables.

Run pytest to make sure everything is set up right.

remove_symbols

Later in the lab, you will use the get_syllable_count() function in the pysyllables module. This function will tell you how many syllables an English word has. However, a word may not include any punctuation or other non-alphabetic characters. For example:

  • get_syllable_count("pond—") returns None
  • get_syllable_count("pond") returns 1
  • get_syllable_count("again.") returns None
  • get_syllable_count("again") returns 2

The remove_symbols() function should remove all characters from a string except for letters and spaces. Start by creating an empty result string. Then loop through the original line, one character at a time. If the character is alphabetic or space, append the character to the result. (Use the isalpha() and isspace() string methods.) Then return the result.

check_syllables

This helper function will be called from validate_haiku() three times. The first parameter (str) represents one line of the haiku. The second parameter (int) is the required number of syllabus. The return value is:

  • "too short" if the number of syllables is less than the number required
  • "valid" if the number of syllables is equal to the number required
  • "too long" if the number of syllables is greater than the number required

Hint: Start by calling remove_symbols() on the line. Then use the split() method to split the string into a list of words.

validate_haiku

This is the main function of the lab. The parameter is a multiline string representing the haiku. If the string is a valid haiku (based on the definition above), the function should return "Valid haiku." (with a period at the end).

If the string has more or less than three lines, the function should return "Invalid haiku, not 3 lines.". If the string has three lines but is not a valid haiku, the function should return a detailed message about the invalid line(s).

  • The format should be "Line X too Y. ", where X is the line number, and Y is either long or short.
  • Each line should end with a single space after the period. Ex: "Line 1 too short. Line 3 too long. "

Hint: Use the splitlines() method to split the string into a list of lines. Then call the check_syllables() function on each line.