Add unit tests of REPL

pom.xml

@@ -32,6 +32,14 @@
                     <target>1.7</target>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.19</version>
+                <configuration>
+                    <argLine>-Dfile.encoding=UTF-8</argLine>
+                </configuration>
+            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>cobertura-maven-plugin</artifactId>

src/main/java/me/predatorray/bud/lisp/BudRepl.java

@@ -32,9 +32,13 @@ public class BudRepl {
     private final boolean interactive;
 
     public BudRepl() {
+        this(true);
+    }
+
+    public BudRepl(boolean interactive) {
         this.evaluator = new NaiveEvaluator();
         this.initial = BuiltinsEnvironment.INSTANCE;
-        this.interactive = true;
+        this.interactive = interactive;
     }
 
     private class ReplParserCallback implements Parser.ParserCallback {
@@ -74,6 +78,9 @@ public void execute(Reader reader, final Writer writer, Writer errorWriter) thro
 
         boolean exceptionOccurred = false;
         while (true) {
+            if (exceptionOccurred) {
+                parser = new Parser(replParserCallback);
+            }
             try {
                 if (interactive) {
                     if (replParserCallback.hasAnyExpressionBeenEvaluated() || exceptionOccurred) {
@@ -89,7 +96,6 @@ public void execute(Reader reader, final Writer writer, Writer errorWriter) thro
                     break;
                 }
 
-                // TODO if ended with backslash
                 Lexer lexer = new Lexer(line);
                 Iterator<Token> tokenIterator = lexer.iterator();
                 parser.feed(tokenIterator);

src/main/java/me/predatorray/bud/lisp/lang/BudString.java

@@ -1,5 +1,6 @@
 package me.predatorray.bud.lisp.lang;
 
+import me.predatorray.bud.lisp.util.StringUtils;
 import me.predatorray.bud.lisp.util.Validation;
 
 public class BudString implements BudObject {
@@ -36,6 +37,6 @@ public int hashCode() {
 
     @Override
     public String toString() {
-        return value;
+        return StringUtils.quote(value);
     }
 }

src/main/java/me/predatorray/bud/lisp/util/Sets.java

@@ -8,6 +8,7 @@
 
 public class Sets {
 
+    @SafeVarargs
     public static <T> Set<T> asSet(T ...ts) {
         Validation.notNull(ts, "sets must not be null");
         return Collections.unmodifiableSet(new HashSet<T>(Arrays.asList(ts)));

src/test/java/me/predatorray/bud/lisp/BudReplTest.java

@@ -0,0 +1,53 @@
+package me.predatorray.bud.lisp;
+
+import me.predatorray.bud.lisp.test.NullWriter;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.*;
+
+import static org.junit.Assert.*;
+
+public class BudReplTest {
+
+    private BudRepl repl;
+
+    @Before
+    public void setUpFixtureOfRepl() {
+        repl = new BudRepl(false);
+    }
+
+    private String readEvaluateAndPrint(String input) throws IOException {
+        try (Reader reader = new StringReader(input);
+             Writer writer = new StringWriter()) {
+            repl.execute(reader, writer, new NullWriter());
+            return writer.toString();
+        }
+    }
+
+    @Test
+    public void testRepl1() throws Exception {
+        String output = readEvaluateAndPrint("\"abc\"");
+        assertEquals("\"abc\"\n", output);
+    }
+
+    @Test
+    public void testRepl2() throws Exception {
+        readEvaluateAndPrint("unknown");
+        String output = readEvaluateAndPrint("\"abc\"");
+        assertEquals("\"abc\"\n", output);
+    }
+
+    @Test
+    public void testRepl3() throws Exception {
+        String output = readEvaluateAndPrint("(+ 1 1) 3");
+        assertEquals("2\n3\n", output);
+    }
+
+    @Test
+    public void testRepl4() throws Exception {
+        String output = readEvaluateAndPrint("(+ 1 1) (\n" +
+                "- 1 1)\n");
+        assertEquals("2\n0\n", output);
+    }
+}

src/test/java/me/predatorray/bud/lisp/test/NullWriter.java

@@ -0,0 +1,19 @@
+package me.predatorray.bud.lisp.test;
+
+import java.io.IOException;
+import java.io.Writer;
+
+public class NullWriter extends Writer {
+
+    @Override
+    public void write(char[] cbuf, int off, int len) throws IOException {
+    }
+
+    @Override
+    public void flush() throws IOException {
+    }
+
+    @Override
+    public void close() throws IOException {
+    }
+}