Reject Uri with empty scheme or host, close #1445

Motivation:

Following #1442, we shouldn't accept Uri with empty scheme or empty
host, such as "http://".

Modifications:

* Introduce MiscUtils#isEmpty(String)
* Throw IllegalArgumentException on empty scheme or host, with message
mentioning missing field and original url

Result:

Better control on Uri that could cause AHC to choke

Author: slandelle

client/src/main/java/org/asynchttpclient/uri/Uri.java

@@ -12,8 +12,8 @@
  */
 package org.asynchttpclient.uri;
 
-import static org.asynchttpclient.util.Assertions.assertNotNull;
-import static org.asynchttpclient.util.MiscUtils.isNonEmpty;
+import static org.asynchttpclient.util.Assertions.assertNotEmpty;
+import static org.asynchttpclient.util.MiscUtils.*;
 
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -36,9 +36,11 @@ public static Uri create(Uri context, final String originalUrl) {
         UriParser parser = new UriParser();
         parser.parse(context, originalUrl);
 
-        if (parser.scheme == null || parser.host == null) {
-            throw new IllegalArgumentException(String.format("The UriParser could not extract all required values: scheme=%s, host=%s. Please make sure you provide a valid URL.",
-                    parser.scheme, parser.host));
+        if (isEmpty(parser.scheme)) {
+            throw new IllegalArgumentException(originalUrl + " could not be parsed into a proper Uri, missing scheme");
+        }
+        if (isEmpty(parser.host)) {
+            throw new IllegalArgumentException(originalUrl + " could not be parsed into a proper Uri, missing host");
         }
 
         return new Uri(parser.scheme,//
@@ -66,9 +68,9 @@ public Uri(String scheme,//
             String path,//
             String query) {
 
-        this.scheme = assertNotNull(scheme, "scheme");
+        this.scheme = assertNotEmpty(scheme, "scheme");
         this.userInfo = userInfo;
-        this.host = assertNotNull(host, "host");
+        this.host = assertNotEmpty(host, "host");
         this.port = port;
         this.path = path;
         this.query = query;

client/src/main/java/org/asynchttpclient/util/Assertions.java

@@ -26,6 +26,7 @@ public static <T> T assertNotNull(T value, String name) {
     }
 
     public static String assertNotEmpty(String value, String name) {
+        assertNotNull(value, name);
         if (value.length() == 0)
             throw new IllegalArgumentException("empty " + name);
         return value;

client/src/main/java/org/asynchttpclient/util/MiscUtils.java

@@ -23,7 +23,11 @@ private MiscUtils() {
     }
 
     public static boolean isNonEmpty(String string) {
-        return string != null && !string.isEmpty();
+        return !isEmpty(string);
+    }
+    
+    public static boolean isEmpty(String string) {
+        return string == null || string.isEmpty();
     }
 
     public static boolean isNonEmpty(Object[] array) {

client/src/test/java/org/asynchttpclient/uri/UriTest.java

@@ -12,10 +12,10 @@
  */
 package org.asynchttpclient.uri;
 
-import org.testng.annotations.Test;
-
 import static org.testng.Assert.*;
 
+import org.testng.annotations.Test;
+
 public class UriTest {
 
     @Test
@@ -360,31 +360,17 @@ public void testIsWebsocket() {
     }
 
     @Test
-    public void testCreateWithInvalidUrl_throwsIllegalArgumentException() {
-        // a valid URL would contain the scheme/protocol
-        String invalidUrl = "localhost";
-
-        Throwable exception = null;
-        try {
-            // run
-            Uri.create(invalidUrl);
-        } catch (IllegalArgumentException ex) {
-            exception = ex;
-        }
+    public void creatingUriWithDefinedSchemeAndHostWorks() {
+        Uri.create("http://localhost");
+    }
 
-        // verify
-        assertNotNull(exception);
-        assertEquals("The UriParser could not extract all required values: scheme=null, host=null. Please make "
-                     + "sure you provide a valid URL.", exception.getMessage());
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    public void creatingUriWithMissingSchemeThrowsIllegalArgumentException() {
+        Uri.create("localhost");
     }
 
-    @Test
-    public void testCreateWithValidUrl_doesNotThrowException() {
-        String validUrl = "https://localhost";
-        try {
-            Uri.create(validUrl);
-        } catch (IllegalArgumentException ex) {
-            fail(ex.getMessage());
-        }
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    public void creatingUriWithMissingHostThrowsIllegalArgumentException() {
+        Uri.create("http://");
     }
 }