Back to Repositories

Testing Terminal Screen Buffer Operations in termux-app

This test suite validates the ScreenBuffer functionality in the Termux terminal emulator, focusing on text manipulation, selection, and buffer management capabilities. The tests ensure accurate character rendering and text selection across multiple screen scenarios.

Test Coverage Overview

The test suite provides comprehensive coverage of terminal buffer operations including:

Basic character insertion and positioning
Block text operations and manipulation
Text selection across multiple lines
Word location and boundary detection
Screen buffer state management

Implementation Analysis

The testing approach utilizes JUnit framework features for systematic validation of the TerminalBuffer class. Tests employ a combination of direct buffer manipulation and helper methods like withTerminalSized() to create controlled test environments.

Key patterns include setup-execute-assert flow and isolated test cases for specific buffer operations.

Technical Details

Testing infrastructure includes:

JUnit test framework
Custom TerminalTestCase base class
TerminalBuffer implementation for screen management
Helper methods for terminal size configuration
Assertion utilities for text comparison

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test methods for specific functionality
Clear test method naming conventions
Comprehensive edge case coverage
Consistent assertion patterns
Modular test setup and teardown

termux/termux-app

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

            
package com.termux.terminal;

public class ScreenBufferTest extends TerminalTestCase {

	public void testBasics() {
		TerminalBuffer screen = new TerminalBuffer(5, 3, 3);
		assertEquals("", screen.getTranscriptText());
		screen.setChar(0, 0, 'a', 0);
		assertEquals("a", screen.getTranscriptText());
		screen.setChar(0, 0, 'b', 0);
		assertEquals("b", screen.getTranscriptText());
		screen.setChar(2, 0, 'c', 0);
		assertEquals("b c", screen.getTranscriptText());
		screen.setChar(2, 2, 'f', 0);
		assertEquals("b c\n\n  f", screen.getTranscriptText());
		screen.blockSet(0, 0, 2, 2, 'X', 0);
	}

	public void testBlockSet() {
		TerminalBuffer screen = new TerminalBuffer(5, 3, 3);
		screen.blockSet(0, 0, 2, 2, 'X', 0);
		assertEquals("XX\nXX", screen.getTranscriptText());
		screen.blockSet(1, 1, 2, 2, 'Y', 0);
		assertEquals("XX\nXYY\n YY", screen.getTranscriptText());
	}

	public void testGetSelectedText() {
		withTerminalSized(5, 3).enterString("ABCDEFGHIJ").assertLinesAre("ABCDE", "FGHIJ", "     ");
		assertEquals("AB", mTerminal.getSelectedText(0, 0, 1, 0));
		assertEquals("BC", mTerminal.getSelectedText(1, 0, 2, 0));
		assertEquals("CDE", mTerminal.getSelectedText(2, 0, 4, 0));
		assertEquals("FG", mTerminal.getSelectedText(0, 1, 1, 1));
		assertEquals("GH", mTerminal.getSelectedText(1, 1, 2, 1));
		assertEquals("HIJ", mTerminal.getSelectedText(2, 1, 4, 1));

		assertEquals("ABCDEFG", mTerminal.getSelectedText(0, 0, 1, 1));
		withTerminalSized(5, 3).enterString("ABCDE\r\nFGHIJ").assertLinesAre("ABCDE", "FGHIJ", "     ");
		assertEquals("ABCDE\nFG", mTerminal.getSelectedText(0, 0, 1, 1));
	}

	public void testGetSelectedTextJoinFullLines() {
		withTerminalSized(5, 3).enterString("ABCDE\r\nFG");
		assertEquals("ABCDEFG", mTerminal.getScreen().getSelectedText(0, 0, 1, 1, true, true));

		withTerminalSized(5, 3).enterString("ABC\r\nFG");
		assertEquals("ABC\nFG", mTerminal.getScreen().getSelectedText(0, 0, 1, 1, true, true));
	}

	public void testGetWordAtLocation() {
		withTerminalSized(5, 3).enterString("ABCDEFGHIJ\r\nKLMNO");
		assertEquals("ABCDEFGHIJKLMNO", mTerminal.getScreen().getWordAtLocation(0, 0));
		assertEquals("ABCDEFGHIJKLMNO", mTerminal.getScreen().getWordAtLocation(4, 1));
		assertEquals("ABCDEFGHIJKLMNO", mTerminal.getScreen().getWordAtLocation(4, 2));

		withTerminalSized(5, 3).enterString("ABC DEF GHI ");
		assertEquals("ABC", mTerminal.getScreen().getWordAtLocation(0, 0));
		assertEquals("", mTerminal.getScreen().getWordAtLocation(3, 0));
		assertEquals("DEF", mTerminal.getScreen().getWordAtLocation(4, 0));
		assertEquals("DEF", mTerminal.getScreen().getWordAtLocation(0, 1));
		assertEquals("DEF", mTerminal.getScreen().getWordAtLocation(1, 1));
		assertEquals("GHI", mTerminal.getScreen().getWordAtLocation(0, 2));
		assertEquals("", mTerminal.getScreen().getWordAtLocation(1, 2));
		assertEquals("", mTerminal.getScreen().getWordAtLocation(2, 2));
	}
}