diff --git a/src/main/scala/gitbucket/core/api/ApiBranch.scala b/src/main/scala/gitbucket/core/api/ApiBranch.scala
index a33f7a9..1852364 100644
--- a/src/main/scala/gitbucket/core/api/ApiBranch.scala
+++ b/src/main/scala/gitbucket/core/api/ApiBranch.scala
@@ -9,7 +9,7 @@
 case class ApiBranch(name: String, commit: ApiBranchCommit, protection: ApiBranchProtection)(
   repositoryName: RepositoryName
 ) extends FieldSerializable {
-  def _links =
+  val _links =
     Map(
       "self" -> ApiPath(s"/api/v3/repos/${repositoryName.fullName}/branches/${name}"),
       "html" -> ApiPath(s"/${repositoryName.fullName}/tree/${name}")
diff --git a/src/test/scala/gitbucket/core/api/ApiSpecModels.scala b/src/test/scala/gitbucket/core/api/ApiSpecModels.scala
index da4024c..6e701c1 100644
--- a/src/test/scala/gitbucket/core/api/ApiSpecModels.scala
+++ b/src/test/scala/gitbucket/core/api/ApiSpecModels.scala
@@ -1,8 +1,11 @@
 package gitbucket.core.api
 
-import java.util.{Calendar, TimeZone, Date}
+import java.util.{Base64, Calendar, Date, TimeZone}
 
+import gitbucket.core.model.Account
+import gitbucket.core.util.JGitUtil.{CommitInfo, DiffInfo}
 import gitbucket.core.util.RepositoryName
+import org.eclipse.jgit.diff.DiffEntry.ChangeType
 
 object ApiSpecModels {
 
@@ -20,16 +23,26 @@
     f.parse(date)
   }
 
+  val account = Account(
+    userName = "octocat",
+    fullName = "octocat",
+    mailAddress = "octocat@example.com",
+    password = "1234",
+    isAdmin = false,
+    url = None,
+    registeredDate = date1,
+    updatedDate = date1,
+    lastLoginDate = Some(date1),
+    image = None,
+    isGroupAccount = false,
+    isRemoved = false,
+    description = None
+  )
+
   val sha1 = "6dcb09b5b57875f334f61aebed695e2e4193db5e"
   val repo1Name = RepositoryName("octocat/Hello-World")
 
-  val apiUser = ApiUser(
-    login = "octocat",
-    email = "octocat@example.com",
-    `type` = "User",
-    site_admin = false,
-    created_at = date1
-  )
+  val apiUser = ApiUser(account)
 
   val repository = ApiRepository(
     name = repo1Name.name,
@@ -167,4 +180,90 @@
     Some(ApiBranchProtection.Status(ApiBranchProtection.Everyone, Seq("continuous-integration/travis-ci")))
   )
 
+  val apiBranch = ApiBranch(
+    name = "master",
+    commit = ApiBranchCommit("468cab6982b37db5eb167568210ec188673fb653"),
+    protection = apiBranchProtection
+  )(
+    repositoryName = repo1Name
+  )
+
+  val apiBranchForList = ApiBranchForList("master", ApiBranchCommit("468cab6982b37db5eb167568210ec188673fb653"))
+
+  val apiPusher = ApiPusher(account)
+
+  val apiEndPoint = ApiEndPoint()
+
+  // TODO use factory method defined in companion object?
+  val apiPlugin = ApiPlugin(
+    id = "gist",
+    name = "Gist Plugin",
+    version = "4.16.0",
+    description = "Provides Gist feature on GitBucket.",
+    jarFileName = "gitbucket-gist-plugin-gitbucket_4.30.0-SNAPSHOT-4.17.0.jar"
+  )
+
+  val apiError = ApiError(
+    message = "A repository with this name already exists on this account",
+    documentation_url = Some("https://developer.github.com/v3/repos/#create")
+  )
+
+  // TODO use factory method defined in companion object?
+  val apiGroup = ApiGroup("octocats", Some("Admin group"), date1)
+
+  val apiRef = ApiRef(
+    ref = "refs/heads/featureA",
+    `object` = ApiObject("aa218f56b14c9653891f9e74264a383fa43fefbd")
+  )
+
+  // TODO use factory method defined in companion object?
+  val apiContents = ApiContents(
+    `type` = "file",
+    name = "README.md",
+    path = "README.md",
+    sha = "3d21ec53a331a6f037a91c368710b99387d012c1",
+    content = Some(Base64.getEncoder.encodeToString("README".getBytes("UTF-8"))),
+    encoding = Some("base64")
+  )(repo1Name)
+
+  val apiCommits = ApiCommits(
+    repositoryName = repo1Name,
+    commitInfo = CommitInfo(
+      id = "3d21ec53a331a6f037a91c368710b99387d012c1",
+      shortMessage = "short message",
+      fullMessage = "full message",
+      parents = List("1da452aa92d7db1bc093d266c80a69857718c406"),
+      authorTime = date1,
+      authorName = "octocat",
+      authorEmailAddress = "octocat@example.com",
+      commitTime = date1,
+      committerName = "octocat",
+      committerEmailAddress = "octocat@example.com"
+    ),
+    diffs = Seq(
+      DiffInfo(
+        changeType = ChangeType.MODIFY,
+        oldPath = "README.md",
+        newPath = "README.md",
+        oldContent = None,
+        newContent = None,
+        oldIsImage = false,
+        newIsImage = false,
+        oldObjectId = None,
+        newObjectId = Some("6dcb09b5b57875f334f61aebed695e2e4193db5e"),
+        oldMode = "old_mode",
+        newMode = "new_mode",
+        tooLarge = false,
+        patch = Some("""@@ -1 +1,2 @@
+          |-body1
+          |\ No newline at end of file
+          |+body1
+          |+body2
+          |\ No newline at end of file""".stripMargin)
+      )
+    ),
+    author = account,
+    committer = account,
+    commentCount = 1
+  )
 }
diff --git a/src/test/scala/gitbucket/core/api/JsonFormatSpec.scala b/src/test/scala/gitbucket/core/api/JsonFormatSpec.scala
index 2c93bba..7b59a40 100644
--- a/src/test/scala/gitbucket/core/api/JsonFormatSpec.scala
+++ b/src/test/scala/gitbucket/core/api/JsonFormatSpec.scala
@@ -255,7 +255,113 @@
         "continuous-integration/travis-ci"
       ]
     }
-}"""
+  }"""
+
+  val apiBranchJson = s"""{
+    "name": "master",
+    "commit": {"sha": "468cab6982b37db5eb167568210ec188673fb653"},
+    "protection": $apiBranchProtectionJson,
+    "_links": {
+      "self": "http://gitbucket.exmple.com/api/v3/repos/octocat/Hello-World/branches/master",
+      "html": "http://gitbucket.exmple.com/octocat/Hello-World/tree/master"
+    }
+  }"""
+
+  val apiBranchForListJson = """{"name": "master", "commit": {"sha": "468cab6982b37db5eb167568210ec188673fb653"}}"""
+
+  val apiPluginJson = """{
+   "id": "gist",
+    "name": "Gist Plugin",
+    "version": "4.16.0",
+    "description": "Provides Gist feature on GitBucket.",
+    "jarFileName": "gitbucket-gist-plugin-gitbucket_4.30.0-SNAPSHOT-4.17.0.jar"
+  }"""
+
+  val apiPusherJson = """{"name":"octocat","email":"octocat@example.com"}"""
+
+  val apiEndPointJson = """{"rate_limit_url":"http://gitbucket.exmple.com/api/v3/rate_limit"}"""
+
+  val apiErrorJson = """{
+    "message": "A repository with this name already exists on this account",
+    "documentation_url": "https://developer.github.com/v3/repos/#create"
+  }"""
+
+  val apiGroupJson = """{
+    "login": "octocats",
+    "description": "Admin group",
+    "created_at": "2011-04-14T16:00:49Z",
+    "id": 0,
+    "url": "http://gitbucket.exmple.com/api/v3/orgs/octocats",
+    "html_url": "http://gitbucket.exmple.com/octocats",
+    "avatar_url": "http://gitbucket.exmple.com/octocats/_avatar"
+  }""".stripMargin
+
+  val apiRefJson = """{
+    "ref": "refs/heads/featureA",
+    "object": {"sha":"aa218f56b14c9653891f9e74264a383fa43fefbd"}
+  }""".stripMargin
+
+  val apiContentsJson =
+    """{
+    "type": "file",
+    "name": "README.md",
+    "path": "README.md",
+    "sha": "3d21ec53a331a6f037a91c368710b99387d012c1",
+    "content": "UkVBRE1F",
+    "encoding": "base64",
+    "download_url": "http://gitbucket.exmple.com/api/v3/repos/octocat/Hello-World/raw/3d21ec53a331a6f037a91c368710b99387d012c1/README.md"
+  }"""
+
+  val apiCommitsJson = s"""{
+    "url": "http://gitbucket.exmple.com/api/v3/repos/octocat/Hello-World/commits/3d21ec53a331a6f037a91c368710b99387d012c1",
+    "sha": "3d21ec53a331a6f037a91c368710b99387d012c1",
+    "html_url": "http://gitbucket.exmple.comoctocat/Hello-World/commit/3d21ec53a331a6f037a91c368710b99387d012c1",
+    "comment_url": "http://gitbucket.exmple.com",
+    "commit": {
+      "url": "http://gitbucket.exmple.com/api/v3/repos/octocat/Hello-World/commits/3d21ec53a331a6f037a91c368710b99387d012c1",
+      "author": {
+        "name": "octocat",
+        "email": "octocat@example.com",
+        "date": "2011-04-14T16:00:49Z"
+      },
+      "committer": {
+        "name": "octocat",
+        "email": "octocat@example.com",
+        "date": "2011-04-14T16:00:49Z"
+      },
+      "message": "short message",
+      "comment_count": 1,
+      "tree": {
+        "url": "http://gitbucket.exmple.com/api/v3/repos/octocat/Hello-World/tree/3d21ec53a331a6f037a91c368710b99387d012c1",
+        "sha": "3d21ec53a331a6f037a91c368710b99387d012c1"
+      }
+    },
+    "author": $apiUserJson,
+    "committer": $apiUserJson,
+    "parents": [
+      {
+        "url": "http://gitbucket.exmple.com/api/v3/repos/octocat/Hello-World/tree/1da452aa92d7db1bc093d266c80a69857718c406",
+        "sha": "1da452aa92d7db1bc093d266c80a69857718c406"
+      }
+    ],
+    "stats": {
+      "additions": 2,
+      "deletions": 1,
+      "total": 3
+    },
+    "files": [
+      {
+        "filename": "README.md",
+        "additions": 2,
+        "deletions": 1,
+        "changes": 3,
+        "status": "modified",
+        "raw_url": "http://gitbucket.exmple.com/octocat/Hello-World/raw/3d21ec53a331a6f037a91c368710b99387d012c1/README.md",
+        "blob_url": "http://gitbucket.exmple.com/octocat/Hello-World/blob/3d21ec53a331a6f037a91c368710b99387d012c1/README.md",
+        "patch": "@@ -1 +1,2 @@\\n-body1\\n\\\\ No newline at end of file\\n+body1\\n+body2\\n\\\\ No newline at end of file"
+      }
+    ]
+  }"""
 
   def assertJson(resultJson: String, expectJson: String) = {
     import java.util.regex.Pattern
@@ -311,4 +417,32 @@
   test("apiBranchProtection") {
     assertJson(JsonFormat(apiBranchProtection), apiBranchProtectionJson)
   }
+  test("apiBranch") {
+    assertJson(JsonFormat(apiBranch), apiBranchJson)
+    assertJson(JsonFormat(apiBranchForList), apiBranchForListJson)
+  }
+  test("apiCommits") {
+    assertJson(JsonFormat(apiCommits), apiCommitsJson)
+  }
+  test("apiContents") {
+    assertJson(JsonFormat(apiContents), apiContentsJson)
+  }
+  test("apiEndPoint") {
+    assertJson(JsonFormat(apiEndPoint), apiEndPointJson)
+  }
+  test("apiError") {
+    assertJson(JsonFormat(apiError), apiErrorJson)
+  }
+  test("apiGroup") {
+    assertJson(JsonFormat(apiGroup), apiGroupJson)
+  }
+  test("apiPlugin") {
+    assertJson(JsonFormat(apiPlugin), apiPluginJson)
+  }
+  test("apiPusher") {
+    assertJson(JsonFormat(apiPusher), apiPusherJson)
+  }
+  test("apiRef") {
+    assertJson(JsonFormat(apiRef), apiRefJson)
+  }
 }