Back to Repositories

Testing Terminal History Buffer Operations in Termux-App

A comprehensive test suite for validating terminal history functionality in the Termux Android terminal emulator. This test class ensures proper handling of terminal scrollback buffer and scroll region operations.

Test Coverage Overview

The test suite covers terminal history management with specific focus on buffer operations and scroll regions.

Key areas tested include:

Basic history buffer operations with varying terminal sizes
Scroll region functionality with DECSTBM commands
Terminal resize handling and history preservation
Edge cases for cursor positioning and line overflow

Implementation Analysis

The testing approach uses JUnit framework with custom assertions for terminal state verification. The implementation leverages the TerminalTestCase base class for common terminal operations and state management.

Notable patterns include:

Fluent interface for terminal operations
Custom assertion methods for terminal state verification
Controlled terminal size manipulation

Technical Details

Testing infrastructure includes:

JUnit test framework
Custom TerminalTestCase extension
Terminal emulation support classes
ANSI escape sequence handling
Mock terminal size configuration

Best Practices Demonstrated

The test suite exemplifies high-quality testing practices with clear test case organization and thorough state verification.

Notable practices include:

Isolated test cases with specific focus areas
Comprehensive state verification after operations
Clear test method naming conventions
Efficient test setup and teardown

termux/termux-app

terminal-emulator/src/test/java/com/termux/terminal/HistoryTest.java

            
package com.termux.terminal;


public class HistoryTest extends TerminalTestCase {

	public void testHistory() {
		final int rows = 3;
		final int cols = 3;
		withTerminalSized(cols, rows).enterString("111222333444555666777888999");
		assertCursorAt(2, 2);
		assertLinesAre("777", "888", "999");
		assertHistoryStartsWith("666", "555");

		resize(cols, 2);
		assertHistoryStartsWith("777", "666", "555");

		resize(cols, 3);
		assertHistoryStartsWith("666", "555");
	}

	public void testHistoryWithScrollRegion() {
		// "CSI P_s ; P_s r" - set Scrolling Region [top;bottom] (default = full size of window) (DECSTBM).
		withTerminalSized(3, 4).enterString("111222333444");
		assertLinesAre("111", "222", "333", "444");
		enterString("\033[2;3r");
		// NOTE: "DECSTBM moves the cursor to column 1, line 1 of the page."
		assertCursorAt(0, 0);
		enterString("\nCDEFGH").assertLinesAre("111", "CDE", "FGH", "444");
		enterString("IJK").assertLinesAre("111", "FGH", "IJK", "444").assertHistoryStartsWith("CDE");
		enterString("LMN").assertLinesAre("111", "IJK", "LMN", "444").assertHistoryStartsWith("FGH", "CDE");
	}

}