diff --git a/lib/common.js b/lib/common.js
index 1a3de1a..5645e26 100755
--- a/lib/common.js
+++ b/lib/common.js
@@ -77,6 +77,7 @@ function boolFromString(value, default_, errName) {
  */
 function jsonStream(arr, stream) {
     stream = stream || process.stdout;
+
     arr.forEach(function (elem) {
         stream.write(JSON.stringify(elem) + '\n');
     });
@@ -89,6 +90,9 @@ function jsonStream(arr, stream) {
  * @param {Array} valid (optional) - an array to validate pairs
  */
 function kvToObj(kvs, valid) {
+    assert.arrayOfString(kvs);
+    assert.optionalArrayOfString(valid);
+
     var o = {};
     for (var i = 0; i < kvs.length; i++) {
         var kv = kvs[i];
@@ -99,7 +103,7 @@ function kvToObj(kvs, valid) {
                 kv));
         var k = kv.slice(0, idx);
         var v = kv.slice(idx + 1);
-        if (valid.indexOf(k) === -1)
+        if (valid && valid.indexOf(k) === -1)
              throw new errors.UsageError(format(
                 'invalid filter name: "%s" (must be one of "%s")',
                 k, valid.join('", "')));
diff --git a/test/unit/common.test.js b/test/unit/common.test.js
index c32079f..169bc96 100644
--- a/test/unit/common.test.js
+++ b/test/unit/common.test.js
@@ -23,6 +23,152 @@ var log = require('../lib/log');
 
 // ---- tests
 
+test('objCopy+deepObjCopy', function (t) {
+    var o1 = {foo: 'bar'};
+    var o2 = {arr: [1,2,3]};
+
+    // shallow copy
+    var c1 = common.objCopy(o1);
+    var c2 = common.objCopy(o2);
+
+    t.notEqual(c1, o1);
+    t.deepEqual(c1, o1);
+
+    t.notEqual(c2, o2);
+    t.deepEqual(c2, o2);
+
+    t.equal(c2.arr, o2.arr);
+
+    var foo = {};
+    common.objCopy(o1, foo);
+    t.notEqual(foo, o1);
+    t.deepEqual(foo, o1);
+
+    // deep copy
+    var d1 = common.deepObjCopy(o1);
+    var d2 = common.deepObjCopy(o2);
+
+    t.notEqual(d1, o1);
+    t.deepEqual(d1, o1);
+
+    t.notEqual(d2, o2);
+    t.deepEqual(d2, o2);
+
+    t.notEqual(d2.arr, o2.arr);
+    t.deepEqual(d2.arr, o2.arr);
+
+    t.end();
+});
+
+test('zeroPad', function (t) {
+    var zp = common.zeroPad;
+
+    t.equal(zp(5, 3), '005');
+    t.equal(zp(50, 3), '050');
+    t.equal(zp(500, 3), '500');
+
+    t.equal(zp('5', 3), '005');
+    t.equal(zp('50', 3), '050');
+    t.equal(zp('500', 3), '500');
+
+    t.end();
+});
+
+test('boolFromString', function (t) {
+    var bfs = common.boolFromString;
+
+    t.equal(bfs(true), true);
+    t.equal(bfs('true'), true);
+    t.equal(bfs('1'), true);
+
+    t.equal(bfs(false), false);
+    t.equal(bfs('false'), false);
+    t.equal(bfs('0'), false);
+
+    t.equal(bfs(undefined, false), false);
+    t.equal(bfs(undefined, true), true);
+    t.equal(bfs(undefined, 'foo'), 'foo');
+
+    t.throws(bfs.bind(null, '2'));
+    t.throws(bfs.bind(null, 500));
+    t.throws(bfs.bind(null, Infinity));
+    t.throws(bfs.bind(null, NaN));
+
+    t.end();
+});
+
+test('jsonStream', function (t) {
+    // TODO this is a lame excuse for a stream
+    var s = '';
+    var stream = {
+        write: function (o) { s += o; }
+    };
+
+    var obj = [
+        'foo',
+        'bar',
+        'baz'
+    ];
+
+    common.jsonStream(obj, stream);
+    t.equal(s, '"foo"\n"bar"\n"baz"\n');
+
+    t.end();
+});
+
+test('kvToObj', function (t) {
+    var arr = ['foo=1', 'bar=2', 'baz=3'];
+    var o = {
+        foo: '1',
+        bar: '2',
+        baz: '3'
+    };
+    var kv;
+
+    // no valid parameter
+    kv = common.kvToObj(arr);
+    t.deepEqual(kv, o);
+
+    // valid parameters
+    kv = common.kvToObj(arr, ['foo', 'bar', 'baz']);
+    t.deepEqual(kv, o);
+
+    // invalid parameters
+    t.throws(function () {
+        common.kvToObj(arr, ['uh-oh']);
+    });
+
+    t.end();
+});
+
+test('longAgo', function (t) {
+    var la = common.longAgo;
+    var now = new Date();
+    var then;
+
+    t.equal(la(now, now), '0s');
+
+    then = now - 1000;
+    t.equal(la(then, now), '1s');
+
+    then = now - 60 * 1000;
+    t.equal(la(then, now), '1m');
+
+    then = now - 60 * 60 * 1000;
+    t.equal(la(then, now), '1h');
+
+    then = now - 24 * 60 * 60 * 1000;
+    t.equal(la(then, now), '1d');
+
+    then = now - 7 * 24 * 60 * 60 * 1000;
+    t.equal(la(then, now), '1w');
+
+    then = now - 365 * 24 * 60 * 60 * 1000;
+    t.equal(la(then, now), '1y');
+
+    t.end();
+});
+
 test('humanDurationFromMs', function (t) {
     var humanDurationFromMs = common.humanDurationFromMs;
     var ms = 1000;