Binary file upload in Postman - Build an Automation Script

Upload a binary file using Postman

Preconditions (3)

Step 1: Open Postman and create a new POST request

Step 2: Enter the API endpoint URL in the request URL field

Step 3: Go to the 'Body' tab

Step 4: Select 'binary' radio button

Step 5: Click 'Select File' and choose the binary file (image.png) from local machine

Step 6: Click 'Send' button to submit the request

✅ Expected Result: The API responds with a success status code (e.g., 200 or 201) and a confirmation message indicating the file was uploaded successfully

Automation Requirements - Postman test scripts

Assertions Needed:

Response status code is 200 or 201

Response body contains confirmation message or success indicator

Best Practices:

Use environment variables for API endpoint URL

Validate response status and body in test scripts

Keep binary file path configurable

Use descriptive test names and comments

Automated Solution

Postman

pm.test('Status code is 200 or 201', function () {
    pm.expect(pm.response.code).to.be.oneOf([200, 201]);
});

pm.test('Response contains success message', function () {
    const jsonData = pm.response.json();
    pm.expect(jsonData.message || jsonData.status).to.match(/success|uploaded/i);
});

The first test checks that the response status code is either 200 or 201, which means the upload was successful.
The second test parses the JSON response body and verifies it contains a success message or status.
Using pm.expect ensures clear assertion failures if the API does not behave as expected.
These tests run automatically after sending the binary file upload request in Postman.

Common Mistakes - 4 Pitfalls

{'mistake': "Not selecting 'binary' option in the Body tab", 'why_bad': 'The file will not be sent as binary data, causing the API to reject or misinterpret the upload', 'correct_approach': "Always select the 'binary' radio button before choosing the file to upload"}

Hardcoding API endpoint URL in multiple requests

Not validating response status code

Assuming response body is always JSON without checking

Bonus Challenge

Now add data-driven testing with 3 different binary files (e.g., image.png, document.pdf, audio.mp3) to upload

Show Hint

Practice

1. In Postman, which Body tab option should you select to upload a binary file?

easy

A. GraphQL

B. Form-data

C. Binary

D. Raw

Solution

1. Step 1: Understand Postman Body tab options

   Postman offers multiple Body tab options like form-data, raw, binary, and GraphQL for different request types.

2. Step 2: Identify the correct option for file upload

   For uploading raw files such as images or documents, the 'Binary' option is used to send the file as-is.

3. Final Answer:

   Binary -> Option C

4. Quick Check:

   Binary option = file upload [OK]

Hint: Use 'Binary' in Body tab to upload files directly [OK]

Common Mistakes:

• Choosing 'form-data' which is for key-value pairs
• Using 'raw' which sends text data, not files
• Selecting 'GraphQL' which is unrelated to file upload

2. Which of the following is the correct way to select a file for binary upload in Postman?

easy

A. Enter file path in URL field

B. Click 'Choose Files' after selecting 'form-data' in Body tab

C. Paste file content in 'raw' Body tab

D. Click 'Select File' after choosing 'binary' in Body tab

Solution

1. Step 1: Identify the correct Body tab for binary upload

   Binary upload requires selecting the 'binary' option in the Body tab.

2. Step 2: Understand file selection process

   After choosing 'binary', Postman shows a 'Select File' button to browse and pick the file to upload.

3. Final Answer:

   Click 'Select File' after choosing 'binary' in Body tab -> Option D

4. Quick Check:

   Binary + Select File = correct file upload [OK]

Hint: Always pick 'Select File' after choosing 'binary' [OK]

Common Mistakes:

• Trying to upload file in 'form-data' without key
• Pasting file content in 'raw' which is for text
• Entering file path in URL which is invalid

3. Given this Postman setup: Body tab set to 'binary' with a valid image file selected, what is the expected server response if the upload succeeds?

medium

A. HTTP 200 OK with success message

B. HTTP 404 Not Found

C. HTTP 500 Internal Server Error

D. HTTP 401 Unauthorized

Solution

1. Step 1: Understand typical server responses for file upload

   A successful file upload usually returns HTTP status 200 OK with a confirmation message.

2. Step 2: Analyze other status codes

   404 means resource missing, 500 means server error, 401 means unauthorized access; none indicate success.

3. Final Answer:

   HTTP 200 OK with success message -> Option A

4. Quick Check:

   Success upload = HTTP 200 OK [OK]

Hint: Success = HTTP 200 OK status [OK]

Common Mistakes:

• Confusing 404 as success
• Assuming 500 means success
• Ignoring authentication errors like 401

4. You tried uploading a binary file in Postman but the server responds with HTTP 400 Bad Request. What is the most likely cause?

medium

A. Server is down

B. File was not selected in the binary Body tab

C. Incorrect HTTP method used

D. File size is zero bytes

Solution

1. Step 1: Understand HTTP 400 Bad Request meaning

   This status means the server could not understand the request due to invalid syntax or missing data.

2. Step 2: Identify common binary upload mistakes

   If no file is selected in the binary Body tab, the request lacks the file data, causing a bad request error.

3. Final Answer:

   File was not selected in the binary Body tab -> Option B

4. Quick Check:

   Missing file = HTTP 400 Bad Request [OK]

Hint: Always select a file before sending binary upload [OK]

Common Mistakes:

• Assuming server down causes 400 error
• Using wrong HTTP method without checking
• Uploading empty files without validation

5. You want to automate testing of binary file uploads in Postman using tests. Which script snippet correctly checks if the upload was successful by verifying HTTP status 200?

hard

A. pm.test('Upload success', () => pm.response.to.have.status(200));

B. pm.test('Upload success', () => pm.response.status === '200');

C. pm.test('Upload success', () => pm.response.code == '200');

D. pm.test('Upload success', () => pm.response.statusCode === 'OK');

Solution

1. Step 1: Understand Postman test syntax

   Postman uses pm.test with a callback function and assertion methods like pm.response.to.have.status(200) to check status codes.

2. Step 2: Evaluate each option's correctness

   pm.test('Upload success', () => pm.response.to.have.status(200)); uses correct assertion syntax. pm.test('Upload success', () => pm.response.status === '200'); incorrectly compares number status to string '200'. pm.test('Upload success', () => pm.response.code == '200'); uses wrong property (code is 'OK') and type. pm.test('Upload success', () => pm.response.statusCode === 'OK'); uses invalid statusCode and string.

3. Final Answer:

   pm.test('Upload success', () => pm.response.to.have.status(200)); -> Option A

4. Quick Check:

   Use pm.response.to.have.status(200) for status check [OK]

Hint: Use pm.response.to.have.status(200) in Postman tests [OK]

Common Mistakes:

• Using equality instead of assertion methods
• Comparing status code as string instead of number
• Using wrong property names for response status