Refactor and add tests for TextBuffer (#738)

src/test/java/dan200/computercraft/core/terminal/TextBufferTest.java

@@ -0,0 +1,150 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2021. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+package dan200.computercraft.core.terminal;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TextBufferTest
+{
+    @Test
+    void testStringConstructor()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        assertEquals( "test", textBuffer.toString() );
+    }
+
+    @Test
+    void testCharRepetitionConstructor()
+    {
+        TextBuffer textBuffer = new TextBuffer( 'a', 5 );
+        assertEquals( "aaaaa", textBuffer.toString() );
+    }
+
+    @Test
+    void testLength()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        assertEquals( 4, textBuffer.length() );
+    }
+
+    @Test
+    void testWrite()
+    {
+        TextBuffer textBuffer = new TextBuffer( ' ', 4 );
+        textBuffer.write( "test" );
+        assertEquals( "test", textBuffer.toString() );
+    }
+
+    @Test
+    void testWriteTextBuffer()
+    {
+        TextBuffer source = new TextBuffer( "test" );
+        TextBuffer target = new TextBuffer( "    " );
+        target.write( source );
+        assertEquals( "test", target.toString() );
+    }
+
+    @Test
+    void testWriteFromPos()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.write( "il", 1 );
+        assertEquals( "tilt", textBuffer.toString() );
+    }
+
+    @Test
+    void testWriteOutOfBounds()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.write( "abcdefghijklmnop", -5 );
+        assertEquals( "fghi", textBuffer.toString() );
+    }
+
+    @Test
+    void testWriteOutOfBounds2()
+    {
+        TextBuffer textBuffer = new TextBuffer( "             " );
+        textBuffer.write( "Hello, world!", -3 );
+        assertEquals( "lo, world!   ", textBuffer.toString() );
+    }
+
+    @Test
+    void testFill()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.fill( 'c' );
+        assertEquals( "cccc", textBuffer.toString() );
+    }
+
+    @Test
+    void testFillSubstring()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.fill( 'c', 1, 3 );
+        assertEquals( "tcct", textBuffer.toString() );
+    }
+
+    @Test
+    void testFillOutOfBounds()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.fill( 'c', -5, 5 );
+        assertEquals( "cccc", textBuffer.toString() );
+    }
+
+    @Test
+    void testCharAt()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        assertEquals( 'e', textBuffer.charAt( 1 ) );
+    }
+
+    @Test
+    void testSetChar()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.setChar( 2, 'n' );
+        assertEquals( "tent", textBuffer.toString() );
+    }
+
+    @Test
+    void testSetCharWithNegativeIndex()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.setChar( -5, 'n' );
+        assertEquals( "test", textBuffer.toString(), "Buffer should not change after setting char with negative index." );
+    }
+
+    @Test
+    void testSetCharWithIndexBeyondBufferEnd()
+    {
+        TextBuffer textBuffer = new TextBuffer( "test" );
+        textBuffer.setChar( 10, 'n' );
+        assertEquals( "test", textBuffer.toString(), "Buffer should not change after setting char beyond buffer end." );
+    }
+
+    @Test
+    void testMultipleOperations()
+    {
+        TextBuffer textBuffer = new TextBuffer( ' ', 5 );
+        textBuffer.setChar( 0, 'H' );
+        textBuffer.setChar( 1, 'e' );
+        textBuffer.setChar( 2, 'l' );
+        textBuffer.write( "lo", 3 );
+        assertEquals( "Hello", textBuffer.toString(), "TextBuffer failed to persist over multiple operations." );
+    }
+
+    @Test
+    void testEmptyBuffer()
+    {
+        TextBuffer textBuffer = new TextBuffer( "" );
+        // exception on writing to empty buffer would fail the test
+        textBuffer.write( "test" );
+        assertEquals( "", textBuffer.toString() );
+    }
+}