add tests for weak.is*()

test/is.js

@@ -0,0 +1,72 @@
+var assert = require('assert');
+var weak = require('../');
+
+describe('weak.isWeakRef()', function () {
+
+  afterEach(gc);
+
+  it('should be true for a `WeakRef` instance', function () {
+    var r = weak({});
+    assert(weak.isWeakRef(r));
+  });
+
+  it('should be false for a normal object', function () {
+    var obj = {};
+    assert(!weak.isWeakRef(obj));
+  });
+
+});
+
+describe('weak.isDead()', function () {
+
+  afterEach(gc);
+
+  it('should be false before the target is gc\'d', function () {
+    var obj = {};
+    var r = weak(obj);
+    assert(!weak.isDead(r));
+  });
+
+  it('should be false inside garbage collection callback', function () {
+    var result;
+    var r = weak({}, function () {
+      result = !weak.isDead(r);
+    });
+    gc();
+    assert(result);
+  });
+
+  it('should be true after the target is gc\'d', function () {
+    var r = weak({});
+    gc();
+    assert(weak.isDead(r));
+  });
+
+});
+
+describe('weak.isNearDeath()', function () {
+
+  afterEach(gc);
+
+  it('should be false before the target is gc\'d', function () {
+    var obj = {};
+    var r = weak(obj);
+    assert(!weak.isNearDeath(r));
+  });
+
+  it('should be true inside garbage collection callback', function () {
+    var result;
+    var r = weak({}, function () {
+      result = weak.isNearDeath(r);
+    });
+    gc();
+    assert(result);
+  });
+
+  it('should be false after the target is gc\'d', function () {
+    var r = weak({});
+    gc();
+    assert(!weak.isNearDeath(r));
+  });
+
+});