diff --git a/package-lock.json b/package-lock.json
index 60e0ed1..c4feaa4 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -171,6 +171,12 @@
         "util": "0.10.3"
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+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-1.0.2.tgz",
+      "integrity": "sha1-E8pRXYYgbaC6xm6DTdOX2HWBCUw=",
+      "dev": true
+    },
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@@ -832,6 +838,12 @@
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       "dev": true
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+    "browser-stdout": {
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+      "resolved": "https://registry.npmjs.org/browser-stdout/-/browser-stdout-1.3.0.tgz",
+      "integrity": "sha1-81HTKWnTL6XXpVZxVCY9korjvR8=",
+      "dev": true
+    },
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@@ -961,6 +973,20 @@
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+    "chai": {
+      "version": "4.1.1",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-4.1.1.tgz",
+      "integrity": "sha1-ZuISeebzxkFf+CMYeCJ5AOIXGzk=",
+      "dev": true,
+      "requires": {
+        "assertion-error": "1.0.2",
+        "check-error": "1.0.2",
+        "deep-eql": "2.0.2",
+        "get-func-name": "2.0.0",
+        "pathval": "1.1.0",
+        "type-detect": "4.0.3"
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@@ -974,6 +1000,12 @@
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+    "check-error": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/check-error/-/check-error-1.0.2.tgz",
+      "integrity": "sha1-V00xLt2Iu13YkS6Sht1sCu1KrII=",
+      "dev": true
+    },
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       "resolved": "https://registry.npmjs.org/chokidar/-/chokidar-1.7.0.tgz",
@@ -1216,6 +1248,23 @@
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       "dev": true
     },
+    "deep-eql": {
+      "version": "2.0.2",
+      "resolved": "https://registry.npmjs.org/deep-eql/-/deep-eql-2.0.2.tgz",
+      "integrity": "sha1-sbrAblbwp2d3aG1Qyf63XC7XZ5o=",
+      "dev": true,
+      "requires": {
+        "type-detect": "3.0.0"
+      },
+      "dependencies": {
+        "type-detect": {
+          "version": "3.0.0",
+          "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-3.0.0.tgz",
+          "integrity": "sha1-RtDMhVOrt7E6NSsNbeov1Y8tm1U=",
+          "dev": true
+        }
+      }
+    },
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       "version": "0.1.3",
       "resolved": "https://registry.npmjs.org/deep-is/-/deep-is-0.1.3.tgz",
@@ -1256,6 +1305,12 @@
         "repeating": "2.0.1"
       }
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+    "diff": {
+      "version": "3.2.0",
+      "resolved": "https://registry.npmjs.org/diff/-/diff-3.2.0.tgz",
+      "integrity": "sha1-yc45Okt8vQsFinJck98pkCeGj/k=",
+      "dev": true
+    },
     "diffie-hellman": {
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       "resolved": "https://registry.npmjs.org/diffie-hellman/-/diffie-hellman-5.0.2.tgz",
@@ -1728,6 +1783,12 @@
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       "dev": true
     },
+    "get-func-name": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/get-func-name/-/get-func-name-2.0.0.tgz",
+      "integrity": "sha1-6td0q+5y4gQJQzoGY2YCPdaIekE=",
+      "dev": true
+    },
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       "resolved": "https://registry.npmjs.org/get-stream/-/get-stream-3.0.0.tgz",
@@ -1811,6 +1872,18 @@
       "integrity": "sha1-Dovf5NHduIVNZOBOp8AOKgJuVlg=",
       "dev": true
     },
+    "graceful-readlink": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/graceful-readlink/-/graceful-readlink-1.0.1.tgz",
+      "integrity": "sha1-TK+tdrxi8C+gObL5Tpo906ORpyU=",
+      "dev": true
+    },
+    "growl": {
+      "version": "1.9.2",
+      "resolved": "https://registry.npmjs.org/growl/-/growl-1.9.2.tgz",
+      "integrity": "sha1-Dqd0NxXbjY3ixe3hd14bRayFwC8=",
+      "dev": true
+    },
     "has-ansi": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/has-ansi/-/has-ansi-2.0.0.tgz",
@@ -2233,6 +2306,12 @@
         "jsonify": "0.0.0"
       }
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+    "json3": {
+      "version": "3.3.2",
+      "resolved": "https://registry.npmjs.org/json3/-/json3-3.3.2.tgz",
+      "integrity": "sha1-PAQ0dD35Pi9cQq7nsZvLSDV19OE=",
+      "dev": true
+    },
     "json5": {
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       "resolved": "https://registry.npmjs.org/json5/-/json5-0.5.1.tgz",
@@ -2324,6 +2403,74 @@
       "integrity": "sha1-eCA6TRwyiuHYbcpkYONptX9AVa4=",
       "dev": true
     },
+    "lodash._baseassign": {
+      "version": "3.2.0",
+      "resolved": "https://registry.npmjs.org/lodash._baseassign/-/lodash._baseassign-3.2.0.tgz",
+      "integrity": "sha1-jDigmVAPIVrQnlnxci/QxSv+Ck4=",
+      "dev": true,
+      "requires": {
+        "lodash._basecopy": "3.0.1",
+        "lodash.keys": "3.1.2"
+      }
+    },
+    "lodash._basecopy": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/lodash._basecopy/-/lodash._basecopy-3.0.1.tgz",
+      "integrity": "sha1-jaDmqHbPNEwK2KVIghEd08XHyjY=",
+      "dev": true
+    },
+    "lodash._basecreate": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/lodash._basecreate/-/lodash._basecreate-3.0.3.tgz",
+      "integrity": "sha1-G8ZhYU2qf8MRt9A78WgGoCE8+CE=",
+      "dev": true
+    },
+    "lodash._getnative": {
+      "version": "3.9.1",
+      "resolved": "https://registry.npmjs.org/lodash._getnative/-/lodash._getnative-3.9.1.tgz",
+      "integrity": "sha1-VwvH3t5G1hzc3mh9ZdPuy6o6r/U=",
+      "dev": true
+    },
+    "lodash._isiterateecall": {
+      "version": "3.0.9",
+      "resolved": "https://registry.npmjs.org/lodash._isiterateecall/-/lodash._isiterateecall-3.0.9.tgz",
+      "integrity": "sha1-UgOte6Ql+uhCRg5pbbnPPmqsBXw=",
+      "dev": true
+    },
+    "lodash.create": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/lodash.create/-/lodash.create-3.1.1.tgz",
+      "integrity": "sha1-1/KEnw29p+BGgruM1yqwIkYd6+c=",
+      "dev": true,
+      "requires": {
+        "lodash._baseassign": "3.2.0",
+        "lodash._basecreate": "3.0.3",
+        "lodash._isiterateecall": "3.0.9"
+      }
+    },
+    "lodash.isarguments": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/lodash.isarguments/-/lodash.isarguments-3.1.0.tgz",
+      "integrity": "sha1-L1c9hcaiQon/AGY7SRwdM4/zRYo=",
+      "dev": true
+    },
+    "lodash.isarray": {
+      "version": "3.0.4",
+      "resolved": "https://registry.npmjs.org/lodash.isarray/-/lodash.isarray-3.0.4.tgz",
+      "integrity": "sha1-eeTriMNqgSKvhvhEqpvNhRtfu1U=",
+      "dev": true
+    },
+    "lodash.keys": {
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/lodash.keys/-/lodash.keys-3.1.2.tgz",
+      "integrity": "sha1-TbwEcrFWvlCgsoaFXRvQsMZWCYo=",
+      "dev": true,
+      "requires": {
+        "lodash._getnative": "3.9.1",
+        "lodash.isarguments": "3.1.0",
+        "lodash.isarray": "3.0.4"
+      }
+    },
     "longest": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/longest/-/longest-1.0.1.tgz",
@@ -2459,6 +2606,65 @@
         "minimist": "0.0.8"
       }
     },
+    "mocha": {
+      "version": "3.5.0",
+      "resolved": "https://registry.npmjs.org/mocha/-/mocha-3.5.0.tgz",
+      "integrity": "sha512-pIU2PJjrPYvYRqVpjXzj76qltO9uBYI7woYAMoxbSefsa+vqAfptjoeevd6bUgwD0mPIO+hv9f7ltvsNreL2PA==",
+      "dev": true,
+      "requires": {
+        "browser-stdout": "1.3.0",
+        "commander": "2.9.0",
+        "debug": "2.6.8",
+        "diff": "3.2.0",
+        "escape-string-regexp": "1.0.5",
+        "glob": "7.1.1",
+        "growl": "1.9.2",
+        "json3": "3.3.2",
+        "lodash.create": "3.1.1",
+        "mkdirp": "0.5.1",
+        "supports-color": "3.1.2"
+      },
+      "dependencies": {
+        "commander": {
+          "version": "2.9.0",
+          "resolved": "https://registry.npmjs.org/commander/-/commander-2.9.0.tgz",
+          "integrity": "sha1-nJkJQXbhIkDLItbFFGCYQA/g99Q=",
+          "dev": true,
+          "requires": {
+            "graceful-readlink": "1.0.1"
+          }
+        },
+        "glob": {
+          "version": "7.1.1",
+          "resolved": "https://registry.npmjs.org/glob/-/glob-7.1.1.tgz",
+          "integrity": "sha1-gFIR3wT6rxxjo2ADBs31reULLsg=",
+          "dev": true,
+          "requires": {
+            "fs.realpath": "1.0.0",
+            "inflight": "1.0.6",
+            "inherits": "2.0.3",
+            "minimatch": "3.0.4",
+            "once": "1.4.0",
+            "path-is-absolute": "1.0.1"
+          }
+        },
+        "has-flag": {
+          "version": "1.0.0",
+          "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-1.0.0.tgz",
+          "integrity": "sha1-nZ55MWXOAXoA8AQYxD+UKnsdEfo=",
+          "dev": true
+        },
+        "supports-color": {
+          "version": "3.1.2",
+          "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-3.1.2.tgz",
+          "integrity": "sha1-cqJiiU2dQIuVbKBf83su2KbiotU=",
+          "dev": true,
+          "requires": {
+            "has-flag": "1.0.0"
+          }
+        }
+      }
+    },
     "ms": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
@@ -2748,6 +2954,12 @@
         "pify": "2.3.0"
       }
     },
+    "pathval": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/pathval/-/pathval-1.1.0.tgz",
+      "integrity": "sha1-uULm1L3mUwBe9rcTYd74cn0GReA=",
+      "dev": true
+    },
     "pbkdf2": {
       "version": "3.0.13",
       "resolved": "https://registry.npmjs.org/pbkdf2/-/pbkdf2-3.0.13.tgz",
@@ -3484,6 +3696,12 @@
         "prelude-ls": "1.1.2"
       }
     },
+    "type-detect": {
+      "version": "4.0.3",
+      "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-4.0.3.tgz",
+      "integrity": "sha1-Dj8mcLRAmbC0bChNE2p+9Jx0wuo=",
+      "dev": true
+    },
     "typedarray": {
       "version": "0.0.6",
       "resolved": "https://registry.npmjs.org/typedarray/-/typedarray-0.0.6.tgz",
diff --git a/package.json b/package.json
index 0f31349..130d294 100644
--- a/package.json
+++ b/package.json
@@ -21,7 +21,9 @@
     "babel-eslint": "^7.2.3",
     "babel-loader": "^7.1.1",
     "babel-preset-es2015": "^6.24.1",
+    "chai": "^4.1.1",
     "eslint": "^4.4.1",
+    "mocha": "^3.5.0",
     "webpack": "^3.5.3"
   }
 }