diff --git a/Tests/Foundation/CPStringTest.j b/Tests/Foundation/CPStringTest.j
index f509e8128a..61aa61a50c 100644
--- a/Tests/Foundation/CPStringTest.j
+++ b/Tests/Foundation/CPStringTest.j
@@ -16,14 +16,112 @@ import <Foundation/CPString.j>
 }
 - (void)testStringByAppendingFormat
 {
-    var format = @"%d X %d = %d";
-    var expectedString = "2 X 3 = 6";
-    var dummyString = @"";
-    var actualString = [dummyString stringByAppendingFormat:format ,2 ,3 ,6];
+    var format = @"%d X %d = %d",
+        expectedString = "2 X 3 = 6",
+        dummyString = @"",
+        actualString = [dummyString stringByAppendingFormat:format, 2, 3, 6];
+        
     [self assertTrue:(expectedString === actualString) 
              message:"stringByAppendingFormat: expected:" + expectedString + " actual:" + actualString];
-    
 }
+
+- (void)testStringWithString
+{
+    var original = [[CPString alloc] initWithString:"str"],
+        copy = [CPString stringWithString:original];
+
+    [self assertTrue:(original == copy) message:"Contents should be equal"];
+}
+
+- (void)testInitWithString
+{
+    var str = [[CPString alloc] initWithString:"str"];
+    [self assert:"str" equals:str];
+}
+
+- (void) testInitWithFormat
+{
+    // this could be really big
+    var str = [[CPString alloc] initWithFormat:"%s", "str"];
+    [self assert:"str" equals:str];
+
+    str = [[CPString alloc] initWithFormat:"%d", 42];
+    [self assert:"42" equals:str];
+
+    str = [[CPString alloc] initWithFormat:"%f", 42.2];
+    [self assert:"42.2" equals:str];    
+}
+
+- (void)testStringWithFormat
+{
+    // this could be equally big
+    var str = [CPString stringWithFormat:"%s", "str"];
+    [self assert:"str" equals:str];
+
+    str = [CPString stringWithFormat:"%d", 42];
+    [self assert:"42" equals:str];
+
+    str = [CPString stringWithFormat:"%f", 42.2];
+    [self assert:"42.2" equals:str];    
+}
+
+- (void)testLength
+{
+    [self assert:0 equals:["" length]];
+    [self assert:1 equals:["a" length]];
+    [self assert:5 equals:["abcde" length]];
+    [self assert:3 equals:["日本語" length]];
+}
+
+- (void)testCharacterAtIndex
+{
+    [self assert:"a" equals:["abcd" characterAtIndex:0]];
+    [self assert:"b" equals:["abcd" characterAtIndex:1]];
+    [self assert:"d" equals:["abcd" characterAtIndex:3]];
+    [self assert:"語" equals:["日本語" characterAtIndex:2]];
+}
+
+- (void)testStringByAppendingSting
+{
+    [self assert:"onetwo" equals:["one" stringByAppendingString:"two"]];
+}
+
+
+- (void)testStringByPaddingToLength
+{
+    [self assert:"onebcd" 
+	  equals:["one" stringByPaddingToLength:6 
+			withString:"abcdefg"
+	                startingAtIndex:1]];
+}
+
+- (void)testComponentsSeparatedByString
+{
+    [self assert:["arash", "francisco", "ross", "tom"]
+	  equals:["arash.francisco.ross.tom" componentsSeparatedByString:"."]];
+}
+
+- (void)testSubstringFromIndex
+{
+    [self assert:"abcd" equals:["abcd" substringFromIndex:0]];
+    [self assert:"bcd"  equals:["abcd" substringFromIndex:1]];
+    [self assert:""     equals:["abcd" substringFromIndex:4]];
+}
+
+- (void)testSubstringWithRange
+{
+    [self assert:"bcd"   equals:["abcde" substringWithRange:CPMakeRange(1,3)]];
+    [self assert:"abcde" equals:["abcde" substringWithRange:CPMakeRange(0,5)]];
+    [self assert:""      equals:["abcde" substringWithRange:CPMakeRange(1,0)]];
+}
+
+- (void)testSubstringToIndex
+{
+    [self assert:"abcd" equals:["abcd" substringToIndex:4]];
+    [self assert:"abc"  equals:["abcd" substringToIndex:3]];
+    [self assert:""     equals:["abcd" substringToIndex:0]];
+}
+
 - (void)testBoolValue
 {
     var testStrings = [