Add SISMEMBER command support for Sets.

- Also, add tests

Author: arnavk

lib/set.js

@@ -86,4 +86,24 @@ exports.scard = function (mockInstance, key, callback) {
   }
 
   mockInstance._callCallback(callback, null, count);
-}
+}
+
+/**
+ * Sismember
+ */
+exports.sismember = function (mockInstance, key, value, callback) {
+  var isMember = 0;
+  if (mockInstance.storage[key]) {
+    if (mockInstance.storage[key].type !== 'set') {
+      var err = new Error('WRONGTYPE Operation against a key holding the wrong kind of value');
+      return mockInstance._callCallback(callback, err);
+    } else {
+      var set = mockInstance.storage[key].value;
+      if (set.indexOf(value) >= 0) {
+        isMember = 1;
+      }
+    }
+  }
+
+  mockInstance._callCallback(callback, null, isMember);
+}

test/redis-mock.set.test.js

@@ -228,3 +228,51 @@ describe('scard', function () {
   });
 
 });
+
+describe('sismember', function () {
+
+  it('should return 1 if the value exists in the set', function (done) {
+    var r = redismock.createClient();
+    r.sadd('foo', 'bar', function (err, result) {
+      r.sismember('foo', 'bar', function (err, result) {
+        result.should.eql(1);
+        r.end();
+        done();
+      });
+    });
+  });
+
+  it('should return 0 if the value does not exist in the set', function (done) {
+    var r = redismock.createClient();
+    r.sadd('foo', 'bar', function (err, result) {
+      r.sismember('foo', 'boo', function (err, result) {
+        result.should.eql(0);
+        r.end();
+        done();
+      });
+    });
+  });
+
+  it('should return 0 if key does not exist', function (done) {
+    var r = redismock.createClient();
+    r.sadd('foo', 'bar', 'baz', function (err, result) {
+      r.sismember('qux', 'bar', function (err, result) {
+        result.should.eql(0);
+        r.end();
+        done();
+      });
+    });
+  });
+
+  it('should return error when the value stored at the key is not a set', function (done) {
+    var r = redismock.createClient();
+    r.hset('foo', 'bar', 'baz', function (err, result) {
+      r.sismember('foo', 'bar', function (err, result) {
+        err.message.should.eql('WRONGTYPE Operation against a key holding the wrong kind of value');
+        r.end();
+        done();
+      });
+    });
+  });
+
+});