Add user exists endpoint (#1135)

src/main/java/org/gitlab4j/api/UserApi.java

@@ -1,6 +1,7 @@
 package org.gitlab4j.api;
 
 import java.io.File;
+import java.io.IOException;
 import java.util.Date;
 import java.util.List;
 import java.util.Objects;
@@ -14,6 +15,7 @@
 import org.gitlab4j.api.GitLabApi.ApiVersion;
 import org.gitlab4j.api.models.CustomAttribute;
 import org.gitlab4j.api.models.Email;
+import org.gitlab4j.api.models.Exists;
 import org.gitlab4j.api.models.GpgKey;
 import org.gitlab4j.api.models.ImpersonationToken;
 import org.gitlab4j.api.models.ImpersonationToken.Scope;
@@ -1413,4 +1415,24 @@ public void deactivateUser(Long userId) throws GitLabApiException {
         }
         post(Response.Status.CREATED, (Form) null, "users", userId, "deactivate");
     }
+
+    /**
+     * Check if the given user exists.
+     *
+     * <pre><code>GitLab Endpoint: POST /users/:username/exists</code></pre>
+     *
+     * @param username the name of the user to check
+     * @throws GitLabApiException if any exception occurs.
+     */
+    public boolean exists(String username) throws GitLabApiException {
+        if (username == null) {
+            throw new RuntimeException("username cannot be null");
+        }
+        try {
+            Response response = get(Response.Status.OK, null, getApiClient().getUrlWithBase("users", username, "exists"));
+            return response.readEntity(Exists.class).getExists();
+        } catch (IOException e) {
+            throw new GitLabApiException(e);
+        }
+    }
 }

src/main/java/org/gitlab4j/api/models/Exists.java

@@ -0,0 +1,24 @@
+package org.gitlab4j.api.models;
+
+import org.gitlab4j.api.utils.JacksonJson;
+
+import java.io.Serializable;
+
+public class Exists implements Serializable {
+    private static final long serialVersionUID = 1L;
+
+    private Boolean exists;
+
+    public Boolean getExists() {
+	    return exists;
+    }
+
+    public void setExists(Boolean exists) {
+	    this.exists = exists;
+    }
+
+    @Override
+    public String toString() {
+        return (JacksonJson.toJsonString(this));
+    }
+}

src/test/java/org/gitlab4j/api/TestUserApi.java

@@ -606,6 +606,16 @@ public void testGpgKeysCurrentUser() throws GitLabApiException {
         assertNull(found);
     }
 
+    @Test
+    public void testUserExists() throws GitLabApiException {
+        User currentUser = gitLabApi.getUserApi().getCurrentUser();
+        assertNotNull(currentUser);
+        assertEquals(TEST_USERNAME, currentUser.getUsername());
+
+        assertTrue(gitLabApi.getUserApi().exists(currentUser.getUsername()));
+        assertFalse(gitLabApi.getUserApi().exists("doesnotexist"));
+    }
+
     public void testGetMemberships() throws GitLabApiException {
         User currentUser = gitLabApi.getUserApi().getCurrentUser();
         assertNotNull(currentUser);