The String library

Chapter lab: Text and datach15-text.zip · 5 KB

This chapter works in a prepared project. Download it before the first task; it unpacks into its own folder.

Or fetch and unpack it from a terminal in VS Code:

bash / zsh
PowerShell

curl -fsSLO https://manykarim.github.io/robotframework-essentials-web/labs/ch15-text.zip && unzip -q ch15-text.zip && rm ch15-text.zip

Invoke-WebRequest https://manykarim.github.io/robotframework-essentials-web/labs/ch15-text.zip -OutFile ch15-text.zip; Expand-Archive ch15-text.zip -DestinationPath .; Remove-Item ch15-text.zip

Open the folder in VS Code with code rfe-ch15-text (or File → Open Folder…) and accept the recommended RobotCode and Python extensions. Then set it up:

uv sync

bash / zsh
PowerShell

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

python -m venv .venv
.venv\Scripts\Activate.ps1
pip install -r requirements.txt

Keep the environment active in every terminal where you run lesson commands.

poetry install --no-root

Python 3.13 or newer is required; uv installs it when it is missing.

Open in browserNo setup? Try the lab right here: its files, an editor and a terminal, running in your browser.

What's inside

Directoryrfe-ch15-text/
- Directory.vscode/
  - extensions.json
- Directorychecks/
  - smoke.robot
- Directorysample_data/
  - app.log
  - catalog.xml
  - orders.csv
  - results.xml
  - settings.cfg
- .gitignore
- .python-version
- LAB.md
- pyproject.toml
- README.md
- requirements.txt
- uv.lock

The String standard library slices and searches text. On the bundled log sample_data/app.log, you can filter lines and count them — a common verification when checking logs for errors. Get Lines Containing String keeps only the matching lines; Get Line Count counts them.

Task 1 — Count the error lines in the log

Edit

Goal: create checks/string.robot that reads the log, filters it to the ERROR lines, and asserts how many there are.

Here is the same filter-and-count over a small built-up string (no file needed). Adapt it to read the log instead.

Worked example — adapt it, don’t copy it

*** Settings ***
Library    String

*** Test Cases ***
Count Matching Lines
    ${text}=    Catenate    SEPARATOR=\n    apple    error    banana    error
    ${matches}=    Get Lines Containing String    ${text}    error
    ${count}=    Get Line Count    ${matches}
    Should Be Equal As Integers    ${count}    2

Done when

the suite imports String and defines Count Error Lines In The Log.

Hint 1

Read the log first — you’ll need OperatingSystem too: ${log}= Get File sample_data/app.log.

Hint 2

Filter to the error lines with Get Lines Containing String ${log} ERROR, count with Get Line Count, and assert the count is 3.

Solution

*** Settings ***
Library    String
Library    OperatingSystem

*** Test Cases ***
Count Error Lines In The Log
    ${log}=    Get File    sample_data/app.log
    ${errors}=    Get Lines Containing String    ${log}    ERROR
    ${count}=    Get Line Count    ${errors}
    Should Be Equal As Integers    ${count}    3

Task 2 — Run it green

Run

Run:

uv run robot checks

robot checks

poetry run robot checks

Done when

the log has exactly three error lines.

Check your understanding

Quick recall. Your first answer stays in this browser; the quiz never blocks your progress.

Which keyword returns lines containing a substring?
Show the answer
Answer: Get Lines Containing String — The String library's Get Lines Containing String returns the matching lines.
Get Line Count returns…
Show the answer
Answer: the number of lines — It counts the lines in a string — handy after filtering.

Key terms

Stringconcept: Standard library for text: split, match, replace, count lines.
Get Lines Containing Stringkeyword: Return the lines of a string that contain a substring.

All terms in the glossary →