Adding tests suites for readAll and readStream

src/common/utils/ensure.js

@@ -1,23 +1,38 @@
 module.exports.notNullOrEmpty = function(value, name) {
   if (value === null)
-    throw new Error(name + " is null.");
+    throw new TypeError(name + " should not be null.");
   if (value === '')
-    throw new Error(name + " is empty.");
+    throw new Error(name + " should not be empty.");
 };
 
 module.exports.notNull = function(value, name) {
   if (value === null)
-    throw new Error(name + " is null.");
+    throw new TypeError(name + " should not be null.");
 };
 
 module.exports.isInteger = function(value, name) {
   if (typeof value !== 'number' || value % 1 !== 0)
-    throw new TypeError(name + " is not an integer.");
+    throw new TypeError(name + " should be an integer.");
 };
 
 module.exports.isArrayOf = function(expectedType, value, name) {
   if (!Array.isArray(value))
-    throw new TypeError(name + " is not an array.");
+    throw new TypeError(name + " should be an array.");
   if (!value.every(function(x) { return x instanceof expectedType; }))
-    throw new TypeError([name, " is not an array of ", expectedType, "."].join(""));
+    throw new TypeError([name, " should be an array of ", expectedType, "."].join(""));
+};
+
+module.exports.isTypeOf = function(expectedType, value, name) {
+  if (!(value instanceof expectedType))
+    throw new TypeError([name, " should be of type '", expectedType, "'."].join(""));
+};
+
+module.exports.positive = function(value, name) {
+  if (value <= 0)
+    throw new Error(name + " should be positive.");
+};
+
+module.exports.nonNegative = function(value, name) {
+  if (value < 0)
+    throw new Error(name + " should be non-negative.");
 };