diff --git a/src/FileUploader.ts b/src/FileUploader.ts
index 7bced7b..8e0b643 100644
--- a/src/FileUploader.ts
+++ b/src/FileUploader.ts
@@ -1,6 +1,7 @@
 import { isLogInRequired, needsRetry, isUrl } from './utils'
 import { CsrfToken } from './types/CsrfToken'
 import { UploadFile } from './types/UploadFile'
+import { ErrorResponse } from './types'
 
 const requestRetryLimit = 5
 
@@ -18,29 +19,31 @@ export class FileUploader {
   private retryCount = 0
 
   public uploadFile(sasJob: string, files: UploadFile[], params: any) {
-    if (files?.length < 1)
-      throw new Error('At least one file must be provided.')
-
-    let paramsString = ''
-
-    for (let param in params) {
-      if (params.hasOwnProperty(param)) {
-        paramsString += `&${param}=${params[param]}`
-      }
-    }
-
-    const program = this.appLoc
-      ? this.appLoc.replace(/\/?$/, '/') + sasJob.replace(/^\//, '')
-      : sasJob
-    const uploadUrl = `${this.serverUrl}${this.jobsPath}/?${
-      '_program=' + program
-    }${paramsString}`
-
-    const headers = {
-      'cache-control': 'no-cache'
-    }
-
     return new Promise((resolve, reject) => {
+      if (files?.length < 1)
+        reject(new ErrorResponse('At least one file must be provided.'))
+      if (!sasJob || sasJob === '')
+        reject(new ErrorResponse('sasJob must be provided.'))
+
+      let paramsString = ''
+
+      for (let param in params) {
+        if (params.hasOwnProperty(param)) {
+          paramsString += `&${param}=${params[param]}`
+        }
+      }
+
+      const program = this.appLoc
+        ? this.appLoc.replace(/\/?$/, '/') + sasJob.replace(/^\//, '')
+        : sasJob
+      const uploadUrl = `${this.serverUrl}${this.jobsPath}/?${
+        '_program=' + program
+      }${paramsString}`
+
+      const headers = {
+        'cache-control': 'no-cache'
+      }
+
       const formData = new FormData()
 
       for (let file of files) {
@@ -76,7 +79,7 @@ export class FileUploader {
         })
         .then((responseText) => {
           if (isLogInRequired(responseText))
-            reject('You must be logged in to upload a file')
+            reject(new ErrorResponse('You must be logged in to upload a file.'))
 
           if (needsRetry(responseText)) {
             if (this.retryCount < requestRetryLimit) {
@@ -95,10 +98,18 @@ export class FileUploader {
             try {
               resolve(JSON.parse(responseText))
             } catch (e) {
-              reject(e)
+              reject(
+                new ErrorResponse(
+                  'Error while parsing json from upload response.',
+                  e
+                )
+              )
             }
           }
         })
+        .catch((err: any) => {
+          reject(new ErrorResponse('Upload request failed.', err))
+        })
     })
   }
 }
diff --git a/src/test/FileUploader.spec.ts b/src/test/FileUploader.spec.ts
new file mode 100644
index 0000000..a9fa746
--- /dev/null
+++ b/src/test/FileUploader.spec.ts
@@ -0,0 +1,137 @@
+import { FileUploader } from '../FileUploader'
+import { UploadFile } from '../types'
+
+const sampleResponse = `{
+  "SYSUSERID": "cas",
+  "_DEBUG":" ",
+  "SYS_JES_JOB_URI": "/jobExecution/jobs/000-000-000-000",
+  "_PROGRAM" : "/Public/app/editors/loadfile",
+  "SYSCC" : "0",
+  "SYSJOBID" : "117382",
+  "SYSWARNINGTEXT" : ""
+}`
+
+const prepareFilesAndParams = () => {
+  const files: UploadFile[] = [
+    {
+      file: new File([''], 'testfile'),
+      fileName: 'testfile'
+    }
+  ]
+  const params = { table: 'libtable' }
+
+  return { files, params }
+}
+
+describe('FileUploader', () => {
+  let originalFetch: any
+  const fileUploader = new FileUploader(
+    '/sample/apploc',
+    'https://sample.server.com',
+    '/jobs/path',
+    null,
+    null
+  )
+
+  beforeAll(() => {
+    originalFetch = (global as any).fetch
+  })
+
+  beforeEach(() => {
+    ;(global as any).fetch = jest.fn().mockImplementation(() =>
+      Promise.resolve({
+        text: () => Promise.resolve(sampleResponse)
+      })
+    )
+  })
+
+  afterAll(() => {
+    ;(global as any).fetch = originalFetch
+  })
+
+  it('should upload successfully', async (done) => {
+    const sasJob = 'test/upload'
+    const { files, params } = prepareFilesAndParams()
+
+    fileUploader.uploadFile(sasJob, files, params).then((res: any) => {
+      expect(JSON.stringify(res)).toEqual(
+        JSON.stringify(JSON.parse(sampleResponse))
+      )
+      done()
+    })
+  })
+
+  it('should an error when no files are provided', async (done) => {
+    const sasJob = 'test/upload'
+    const files: UploadFile[] = []
+    const params = { table: 'libtable' }
+
+    fileUploader.uploadFile(sasJob, files, params).catch((err: any) => {
+      expect(err.error.message).toEqual('At least one file must be provided.')
+      done()
+    })
+  })
+
+  it('should throw an error when no sasJob is provided', async (done) => {
+    const sasJob = ''
+    const { files, params } = prepareFilesAndParams()
+
+    fileUploader.uploadFile(sasJob, files, params).catch((err: any) => {
+      expect(err.error.message).toEqual('sasJob must be provided.')
+      done()
+    })
+  })
+
+  it('should throw an error when login is required', async (done) => {
+    ;(global as any).fetch = jest.fn().mockImplementation(() =>
+      Promise.resolve({
+        text: () => Promise.resolve('<form action="Logon">')
+      })
+    )
+
+    const sasJob = 'test'
+    const { files, params } = prepareFilesAndParams()
+
+    fileUploader.uploadFile(sasJob, files, params).catch((err: any) => {
+      expect(err.error.message).toEqual(
+        'You must be logged in to upload a file.'
+      )
+      done()
+    })
+  })
+
+  it('should throw an error when invalid JSON is returned by the server', async (done) => {
+    ;(global as any).fetch = jest.fn().mockImplementation(() =>
+      Promise.resolve({
+        text: () => Promise.resolve('{invalid: "json"')
+      })
+    )
+
+    const sasJob = 'test'
+    const { files, params } = prepareFilesAndParams()
+
+    fileUploader.uploadFile(sasJob, files, params).catch((err: any) => {
+      expect(err.error.message).toEqual(
+        'Error while parsing json from upload response.'
+      )
+      done()
+    })
+  })
+
+  it('should throw an error when the server request fails', async (done) => {
+    ;(global as any).fetch = jest.fn().mockImplementation(() =>
+      Promise.resolve({
+        text: () => Promise.reject('{message: "Server error"}')
+      })
+    )
+
+    const sasJob = 'test'
+    const { files, params } = prepareFilesAndParams()
+
+    fileUploader.uploadFile(sasJob, files, params).catch((err: any) => {
+      expect(err.error.message).toEqual('Upload request failed.')
+
+      done()
+    })
+  })
+})
diff --git a/src/utils/parseGeneratedCode.spec.ts b/src/test/utils/parseGeneratedCode.spec.ts
similarity index 96%
rename from src/utils/parseGeneratedCode.spec.ts
rename to src/test/utils/parseGeneratedCode.spec.ts
index 116a88f..d08108d 100644
--- a/src/utils/parseGeneratedCode.spec.ts
+++ b/src/test/utils/parseGeneratedCode.spec.ts
@@ -1,4 +1,4 @@
-import { parseGeneratedCode } from './index'
+import { parseGeneratedCode } from '../../utils/index'
 
 it('should parse generated code', async (done) => {
   expect(sampleResponse).toBeTruthy()
diff --git a/src/utils/parseSourceCode.spec.ts b/src/test/utils/parseSourceCode.spec.ts
similarity index 95%
rename from src/utils/parseSourceCode.spec.ts
rename to src/test/utils/parseSourceCode.spec.ts
index d407d49..4e779cb 100644
--- a/src/utils/parseSourceCode.spec.ts
+++ b/src/test/utils/parseSourceCode.spec.ts
@@ -1,4 +1,4 @@
-import { parseSourceCode } from './index'
+import { parseSourceCode } from '../../utils/index'
 
 it('should parse SAS9 source code', async (done) => {
   expect(sampleResponse).toBeTruthy()
diff --git a/src/types/ErrorResponse.ts b/src/types/ErrorResponse.ts
index c00822a..85635df 100644
--- a/src/types/ErrorResponse.ts
+++ b/src/types/ErrorResponse.ts
@@ -1,5 +1,5 @@
 export class ErrorResponse {
-  body: ErrorBody
+  error: ErrorBody
 
   constructor(message: string, details?: any) {
     let detailsString = ''
@@ -11,7 +11,7 @@ export class ErrorResponse {
       raw = details
     }
 
-    this.body = {
+    this.error = {
       message,
       details: detailsString,
       raw