transcendental-lisp/test/scanner/LispFilterInputStreamTester.java

package scanner;

import static org.junit.Assert.assertEquals;

import java.io.InputStream;

import org.junit.Before;
import org.junit.Test;

import testutils.TestUtilities;

public class LispFilterInputStreamTester {

    private StringBuilder charactersRead;

    @Before
    public void setUp() {
        charactersRead = new StringBuilder();
    }

    @Test
    public void noBytesIn_noBytesOut() {
        String input = "";

        assertEquals(input, getLispFilterInputStreamResult(input));
    }

    @Test
    public void oneCharacter_notRemoved() {
        String input = "x";

        assertEquals(input, getLispFilterInputStreamResult(input));
    }

    @Test
    public void allNonCommentCharacters_notRemoved() {
        String input = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
                       + "`1234567890-=~!@#$%^&*()_+[]\\',./{}|:\"<>?";

        assertEquals(input, getLispFilterInputStreamResult(input));
    }

    @Test
    public void oneComment_Removed() {
        String input = ";comment";
        String expectedResult = "";

        assertEquals(expectedResult, getLispFilterInputStreamResult(input));
    }

    @Test
    public void multipleComments_Removed() {
        String input = ";comment1\n;comment2\n;comment3";
        String expectedResult = "\n\n";

        assertEquals(expectedResult, getLispFilterInputStreamResult(input));
    }

    @Test
    public void nil_NotRemoved() {
        String input = "()";
        String expectedResult = "()";

        assertEquals(expectedResult, getLispFilterInputStreamResult(input));
    }

    @Test
    public void interiorComment_Removed() {
        String input = "(;this is a comment\n)";
        String expectedResult = "(\n)";

        assertEquals(expectedResult, getLispFilterInputStreamResult(input));
    }

    @Test
    public void commentInString_NotRemoved() {
        String input = "\"string;this should remain\"";

        assertEquals(input, getLispFilterInputStreamResult(input));
    }

    @Test
    public void commentInStringWithNewline_NotRemoved() {
        String input = "\"string;this should\n remain\"";

        assertEquals(input, getLispFilterInputStreamResult(input));
    }

    @Test
    public void commentInStringWithEscapedDoubleQuote_NotRemoved() {
        String input = "\"string \\\" ;this should remain\"";

        assertEquals(input, getLispFilterInputStreamResult(input));
    }

    @Test
    public void manyCommentsWithStatements_OnlyCommentsRemoved() {
        String input = ";first comment \n '(1 2 3) \n ;second comment \n (defun add1 (x) (+ x 1)) ;third comment";
        String expectedResult = "\n '(1 2 3) \n \n (defun add1 (x) (+ x 1)) ";

        assertEquals(expectedResult, getLispFilterInputStreamResult(input));
    }

    @Test
    public void unreadOneCharacter_ReturnsSameCharacter() {
        String input = "abc";
        char expectedResult = 'a';
        LispInputStream lispInputStream = createLispInputStream(input);

        lispInputStream.read();
        lispInputStream.unreadLastCharacter();

        assertEquals(expectedResult, lispInputStream.read());
    }

    @Test
    public void unreadAndRereadSameCharacterMultipleTimes_ReturnsSameCharacter() {
        String input = "abc";
        char expectedResult = 'a';
        LispInputStream lispInputStream = createLispInputStream(input);

        lispInputStream.read();
        lispInputStream.unreadLastCharacter();
        lispInputStream.read();
        lispInputStream.unreadLastCharacter();
        lispInputStream.read();
        lispInputStream.unreadLastCharacter();

        assertEquals(expectedResult, lispInputStream.read());
    }

    @Test
    public void unreadOneCharacterAndRereadIt_ReturnsNextCharacterOnNextRead() {
        String input = "abc";
        char expectedResult = 'b';
        LispInputStream lispInputStream = createLispInputStream(input);

        lispInputStream.read();
        lispInputStream.unreadLastCharacter();
        lispInputStream.read();

        assertEquals(expectedResult, lispInputStream.read());
    }

    @Test(expected = LispInputStream.MaximumUnreadsExceededException.class)
    public void callUnreadMultipleTimes_ThrowsException() {
        String input = "abc";
        LispInputStream lispInputStream = createLispInputStream(input);

        lispInputStream.read();
        lispInputStream.unreadLastCharacter();
        lispInputStream.unreadLastCharacter();
    }

    @Test
    public void unreadNewlineInStringAfterComment_ReturnsNewline() {
        String input = "a;123\n";
        char expectedResult = '\n';
        LispInputStream lispInputStream = createLispInputStream(input);

        lispInputStream.read();
        lispInputStream.read();
        lispInputStream.unreadLastCharacter();

        assertEquals(expectedResult, lispInputStream.read());
    }

    private String getLispFilterInputStreamResult(String inputString) {
        return readInputStreamIntoString(createLispInputStream(inputString));
    }

    private LispInputStream createLispInputStream(String inputString) {
        InputStream stringInputStream = TestUtilities.createInputStreamFromString(inputString);

        return new LispFilterInputStream(stringInputStream);
    }

    private String readInputStreamIntoString(LispInputStream inputStream) {
        int c = inputStream.read();

        while (c != -1) {
            charactersRead.append((char) c);
            c = inputStream.read();
        }

        return charactersRead.toString();
    }

}