Fix the true.type() == "boolean"

Fix the true.type() == "boolean" instead of java.lang.Boolean.

Remove all the references to "error" result  in Type(). This will be addressed in:
@ToDo fix this with issue #2562

main/src/com/google/refine/expr/functions/Type.java

@@ -57,8 +57,10 @@ public class Type implements Function {
                     return "number";
                 } else if (v.getClass().isArray() || v instanceof List<?>) {
                     return "array";
-                } else if (v instanceof EvalError) {
+                } else if (v instanceof Boolean) {
-                    return "error";
+                    return "boolean";
+//                } else if (v instanceof EvalError) { // @ToDo fix this with issue #2562
+//                    return "error";
                 } else {
                     return v.getClass().getName();
                 }
@@ -70,7 +72,7 @@ public class Type implements Function {
 
     @Override
     public String getDescription() {
-        return "Returns the type of o";
+        return "Returns the type of o as a string ('string', 'date', 'number', 'array', 'boolean' or a class name)";
     }
     
     @Override

main/tests/server/src/com/google/refine/expr/functions/TypeTests.java

@@ -26,15 +26,83 @@
  ******************************************************************************/
 package com.google.refine.expr.functions;
 
+import java.time.OffsetDateTime;
+import java.time.format.DateTimeFormatter;
+
+import org.slf4j.LoggerFactory;
+import org.testng.Assert;
+import org.testng.annotations.AfterMethod;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.BeforeTest;
 import org.testng.annotations.Test;
 
+import java.util.Arrays;
+import java.util.List;
+import java.util.Properties;
+
+import com.google.refine.RefineTest;
+import com.google.refine.expr.EvalError;
 import com.google.refine.expr.functions.Type;
+import com.google.refine.grel.ControlFunctionRegistry;
+import com.google.refine.grel.Function;
 import com.google.refine.util.TestUtils;
 
-public class TypeTests {
+
+public class TypeTests extends RefineTest {
+    private static Properties bindings;
+    static final List<String> listArray = Arrays.asList("v1", "v2", "v3");
+    private static OffsetDateTime dateTimeValue = OffsetDateTime.parse("2017-05-12T05:45:00+00:00", DateTimeFormatter.ISO_OFFSET_DATE_TIME);
+
+    @Override
+    @BeforeTest
+    public void init() {
+        logger = LoggerFactory.getLogger(this.getClass());
+    }
+
+    @BeforeMethod
+    public void setUp() {
+        bindings = new Properties();
+    }
+
+    @AfterMethod
+    public void tearDown() {
+        bindings = null;
+    }
+
+    /**
+     * Lookup a control function by name and invoke it with a variable number of args
+     */
+    private static Object invoke(String name,Object... args) {
+        // registry uses static initializer, so no need to set it up
+        Function function = ControlFunctionRegistry.getFunction(name);
+        if (function == null) {
+            throw new IllegalArgumentException("Unknown function "+name);
+        }
+        if (args == null) {
+            return function.call(bindings,new Object[0]);
+        } else {
+            return function.call(bindings,args);
+        }
+    }
+
+    @Test
+    public void testTypeInvalidParams() {
+        Assert.assertTrue(invoke("type") instanceof EvalError);
+    }
+
+    @Test
+    public void testType() {
+        Assert.assertEquals(invoke("type", (Object) null),"undefined");
+        Assert.assertEquals(invoke("type", 1),"number");
+        Assert.assertEquals(invoke("type", true),"boolean");
+        Assert.assertEquals(invoke("type", "a string"),"string");
+        Assert.assertEquals(invoke("type", dateTimeValue), "date");
+        Assert.assertEquals(invoke("type", listArray), "array");
+    }
+
     @Test
     public void serializeType() {
-        String json = "{\"description\":\"Returns the type of o\",\"params\":\"object o\",\"returns\":\"string\"}";
+        String json = "{\"description\":\"Returns the type of o as a string ('string', 'date', 'number', 'array', 'boolean' or a class name)\",\"params\":\"object o\",\"returns\":\"string\"}";
         TestUtils.isSerializedTo(new Type(), json);
     }
 }