Added unit tests and refactored the load function

src/function/builtin/LOAD.java

@@ -1,82 +1,84 @@
 package function.builtin;
 
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
+import java.io.*;
+import java.text.MessageFormat;
 
-import function.LispFunction;
-import function.builtin.cons.LENGTH;
+import environment.Environment;
+import function.*;
 import parser.LispParser;
 import sexpression.*;
 
-/**
- * <code>LOAD</code> represents the LOAD function in Lisp.
- */
 public class LOAD extends LispFunction {
-    // The number of arguments that LOAD takes.
-    private static final int NUM_ARGS = 1;
 
-    public SExpression call(Cons argList) {
-        // retrieve the number of arguments passed to LOAD
-        int argListLength = LENGTH.getLength(argList);
+    private ArgumentValidator argumentValidator;
+    private Environment environment;
 
-        // make sure we have received the proper number of arguments
-        if (argListLength != NUM_ARGS) {
-            Cons originalSExpr = new Cons(new Symbol("LOAD"), argList);
-            String errMsg = "too " +
-                            ((argListLength > NUM_ARGS) ? "many" : "few") +
-                            " arguments given to LOAD: " + originalSExpr;
+    public LOAD() {
+        this.argumentValidator = new ArgumentValidator("LOAD");
+        this.argumentValidator.setExactNumberOfArguments(1);
+        this.argumentValidator.setEveryArgumentExpectedType(LispString.class);
+        this.environment = Environment.getInstance();
+    }
 
-            throw new RuntimeException(errMsg);
-        }
+    public SExpression call(Cons argumentList) {
+        argumentValidator.validate(argumentList);
 
-        SExpression argCar = argList.getCar();
-
-        // make sure the argument is a string
-        if (! argCar.stringp()) {
-            throw new RuntimeException("LOAD: " + argCar + " is not a string");
-        }
-
-        LispString quotedName = (LispString) argCar;
-        String fileName = quotedName.toString();
-
-        // remove the surrounding quotes from the file name
-        fileName = fileName.substring(1, (fileName.length() - 1));
+        LispString quotedName = (LispString) argumentList.getCar();
+        String fileName = removeSurroundingQuotes(quotedName.toString());
 
         return processFile(fileName);
     }
 
-    // Evaluate all the S-expressions found in the file with the specified
-    // name.
-    //
-    // Parameters: fileName - the name of the file to be evaluated
-    // Returns: 'T' if the file was processed successfully; 'NIL' otherwise
+    private String removeSurroundingQuotes(String fileName) {
+        return fileName.substring(1, (fileName.length() - 1));
+    }
+
     private SExpression processFile(String fileName) {
+        boolean wasSuccessful = false;
+        LispParser parser = attemptToCreateParserOnFile(fileName);
+
+        if (parser != null)
+            wasSuccessful = isSuccessfulEvaluation(parser);
+
+        return wasSuccessful ? Symbol.T : Nil.getInstance();
+    }
+
+    private LispParser attemptToCreateParserOnFile(String fileName) {
         LispParser parser = null;
 
-        // attempt to create a new 'LispParser' on the specified file
         try {
             parser = new LispParser(new FileInputStream(fileName), fileName);
         } catch (FileNotFoundException e) {
-            System.out.println("LOAD: could not open " + fileName);
-
-            return Nil.getInstance();
+            printCouldNotOpenFileMessage(fileName);
         }
 
-        // attempt to evaluate all the S-expressions contained in the file
-        while (! parser.isEof()) {
+        return parser;
+    }
+
+    private boolean isSuccessfulEvaluation(LispParser parser) {
+        while (!parser.isEof()) {
             try {
                 SExpression sexpr = parser.getNextSExpression();
 
                 EVAL.eval(sexpr);
             } catch (RuntimeException e) {
-                System.out.println("LOAD: " + e.getMessage());
+                printErrorMessage(e.getMessage());
 
-                return Nil.getInstance();
+                return false;
             }
         }
         
-        // success!
-        return Symbol.T;
+        return true;
+    }
+
+    private void printCouldNotOpenFileMessage(String fileName) {
+        String message = MessageFormat.format("could not open ''{0}''", fileName);
+        printErrorMessage(message);
+    }
+
+    private void printErrorMessage(String errorMessage) {
+        String message = MessageFormat.format("LOAD: {0}", errorMessage);
+        environment.getErrorOutput().println(message);
     }
 
 }

src/function/builtin/special/LET.java

@@ -5,9 +5,6 @@ import function.builtin.EVAL;
 import sexpression.*;
 import table.SymbolTable;
 
-/**
- * <code>LET</code> represents the LET form in Lisp.
- */
 public class LET extends LispFunction {
 
     public SExpression call(Cons argList) {
@@ -93,11 +90,6 @@ public class LET extends LispFunction {
         }
     }
 
-    /**
-     * Determine if the arguments passed to this Lisp function should be evaluated.
-     *
-     * @return <code>false</code>
-     */
     public boolean evaluateArguments() {
         return false;
     }

test/function/builtin/LOADTester.java

@@ -0,0 +1,69 @@
+package function.builtin;
+
+import static org.junit.Assert.assertEquals;
+import static testutil.TestUtilities.*;
+
+import java.io.*;
+
+import org.junit.*;
+
+import environment.Environment;
+import function.ArgumentValidator.*;
+
+public class LOADTester {
+
+    private ByteArrayOutputStream outputStream;
+
+    private void assertPrinted(String expected) {
+        assertEquals(expected, outputStream.toString());
+    }
+
+    private void assertNothingPrinted() {
+        assertPrinted("");
+    }
+
+    @Before
+    public void setUp() {
+        this.outputStream = new ByteArrayOutputStream();
+        Environment.getInstance().setErrorOutput(new PrintStream(outputStream));
+    }
+
+    @Test
+    public void loadGoodFile_ReturnsTAndPrintsNothing() {
+        String input = "(load \"test/function/builtin/test-files/load-good.lisp\")";
+
+        assertSExpressionsMatch(parseString("T"), evaluateString(input));
+        assertNothingPrinted();
+    }
+    @Test
+    public void loadBadFile_ReturnsNilAndPrintsError() {
+        String input = "(load \"test/function/builtin/test-files/load-bad.lisp\")";
+
+        assertSExpressionsMatch(parseString("nil"), evaluateString(input));
+        assertPrinted("LOAD: expression begins with ')' - line 1, column 1\n");
+    }
+
+    @Test
+    public void loadNonExistentFile_ReturnsNilAndPrintsError() {
+        String input = "(load \"doesNotExist.lisp\")";
+
+        assertSExpressionsMatch(parseString("nil"), evaluateString(input));
+        assertPrinted("LOAD: could not open 'doesNotExist.lisp'\n");
+    }
+
+    @Test(expected = BadArgumentTypeException.class)
+    public void testLoadWithBadArgumentType() {
+        evaluateString("(load '1)");
+    }
+
+    @Test(expected = TooManyArgumentsException.class)
+    public void testLoadWithTooManyArguments() {
+        evaluateString("(load \"1\" \"2\")");
+    }
+
+    @Test(expected = TooFewArgumentsException.class)
+    public void testLoadWithTooFewArguments() {
+        evaluateString("(load)");
+    }
+
+}

test/function/builtin/test-files/load-bad.lisp

@@ -0,0 +1,50 @@
+)(defun extend-null (the-list)
+  (cond
+   ((equal (length the-list) 0) t)
+   (t nil)
+  )
+)
+
+(defun mapcar (function-name the-list)
+  (cond
+   ((null the-list) nil)
+   (t (cons (funcall function-name (first the-list))
+	    (mapcar function-name (rest the-list))))
+  )
+)
+
+(defun maplist (function-name the-list)
+  (cond
+   ((null the-list) nil)
+   (t (cons (funcall function-name the-list)
+	    (maplist function-name (rest the-list))))
+  )
+)
+
+(defun extend-apply (function-name param-list)
+  (eval (cons function-name param-list)))
+
+(defun append (listA listB)
+  (cond
+   ((null listA) listB)
+   (t (cons (first listA) (append (rest listA) listB)))
+  )
+)
+
+(defun second (listA) (first (rest listA)))
+(defun third (listA) (first (rest (rest listA))))
+(defun fourth (listA) (first (rest (rest (rest listA)))))
+(defun fifth (listA) (first (rest (rest (rest (rest listA))))))
+(defun sixth (listA) (first (rest (rest (rest (rest (rest listA)))))))
+(defun seventh (listA) (first (rest (rest (rest (rest (rest (rest listA))))))))
+(defun eighth (listA) (first (rest (rest (rest (rest (rest (rest (rest listA)))))))))
+(defun ninth (listA) (first (rest (rest (rest (rest (rest (rest (rest (rest listA))))))))))
+(defun tenth (listA) (first (rest (rest (rest (rest (rest (rest (rest (rest (rest listA)))))))))))
+
+(defun nth (n listA)
+  (cond
+   ((equal 0 n) (first listA))
+   (t (nth (- n 1) (rest listA)))
+  )
+)
+

test/function/builtin/test-files/load-good.lisp

@@ -0,0 +1,50 @@
+(defun extend-null (the-list)
+  (cond
+   ((equal (length the-list) 0) t)
+   (t nil)
+  )
+)
+
+(defun mapcar (function-name the-list)
+  (cond
+   ((null the-list) nil)
+   (t (cons (funcall function-name (first the-list))
+	    (mapcar function-name (rest the-list))))
+  )
+)
+
+(defun maplist (function-name the-list)
+  (cond
+   ((null the-list) nil)
+   (t (cons (funcall function-name the-list)
+	    (maplist function-name (rest the-list))))
+  )
+)
+
+(defun extend-apply (function-name param-list)
+  (eval (cons function-name param-list)))
+
+(defun append (listA listB)
+  (cond
+   ((null listA) listB)
+   (t (cons (first listA) (append (rest listA) listB)))
+  )
+)
+
+(defun second (listA) (first (rest listA)))
+(defun third (listA) (first (rest (rest listA))))
+(defun fourth (listA) (first (rest (rest (rest listA)))))
+(defun fifth (listA) (first (rest (rest (rest (rest listA))))))
+(defun sixth (listA) (first (rest (rest (rest (rest (rest listA)))))))
+(defun seventh (listA) (first (rest (rest (rest (rest (rest (rest listA))))))))
+(defun eighth (listA) (first (rest (rest (rest (rest (rest (rest (rest listA)))))))))
+(defun ninth (listA) (first (rest (rest (rest (rest (rest (rest (rest (rest listA))))))))))
+(defun tenth (listA) (first (rest (rest (rest (rest (rest (rest (rest (rest (rest listA)))))))))))
+
+(defun nth (n listA)
+  (cond
+   ((equal 0 n) (first listA))
+   (t (nth (- n 1) (rest listA)))
+  )
+)
+