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This guide covers the practical steps to test your visualization locally using the parser CLI. For full parser CLI documentation, see Parser CLI Development.

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Prerequisites

Before testing, ensure you have:
  • The parser_cli binary built (see installation instructions)
  • A raw transaction hex from your DApp or protocol
  • The expected output you want to verify

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Quick testing workflow

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1. Parse your transaction

Run the parser CLI with your transaction: 
parser_cli --chain <chain> -t <your_transaction_hex> --output human
For example, with an Ethereum transaction: 
parser_cli --chain ethereum -t 0x02f9... --output human

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2. Verify the output

Check that the visualization:
  • Shows the correct action (swap, transfer, approval, etc.)
  • Displays accurate amounts and addresses
  • Uses appropriate labels that users will understand

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3. Test the condensed view

Hardware wallets have limited screen space. Verify your visualization works in condensed mode: 
parser_cli --chain <chain> -t <your_transaction_hex> --output human --condensed-only
The condensed view should show only the most critical information.

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4. Check JSON output

For programmatic validation, use JSON output: 
parser_cli --chain <chain> -t <your_transaction_hex> --output json
You can extract specific fields with jq: 
parser_cli --chain ethereum -t <tx_hex> --output json | jq '.Fields'

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Common issues

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Transaction fails to parse

Cause: Incorrect chain type or malformed hex encoding. Solution: Verify the chain flag matches your transaction and that the hex is properly formatted (with or without 0x prefix, depending on chain conventions).

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Missing protocol details

Cause: The parser does not recognize your contract or protocol. Solution: You may need to add a protocol-specific preset. See Creating Visualizations for patterns.

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Output too verbose for hardware wallets

Cause: The condensed view includes too many fields. Solution: Review your visualization’s Condensed section in the PreviewLayout and reduce it to only the essential fields.

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Amounts display incorrectly

Cause: Decimal handling or token metadata issues. Solution: Verify that token decimals are correctly applied. Use the amount_v2 field type with proper Amount and Abbreviation values.

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Adding test fixtures

When your visualization is working, add a test fixture to ensure it does not regress.

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1. Save your transaction

Create a fixture file in the appropriate chain directory: 
src/chain_parsers/visualsign-<chain>/tests/fixtures/
Name the file descriptively, for example my_protocol_swap.input.

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2. Add expected output

Create a corresponding expected output file with the same name but .expected extension. This captures the correct JSON output for comparison.

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3. Write a test

Add a test that compares the parser output against your expected fixture: 
#[test]
fn test_my_protocol_swap() {
    let input = include_str!("fixtures/my_protocol_swap.input");
    let expected = include_str!("fixtures/my_protocol_swap.expected");

    let result = parse_transaction(input);
    assert_eq!(result, expected);
}

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4. Run tests

Verify your fixture passes: 
cargo test -p visualsign-<chain> test_my_protocol

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Validation checklist

Before submitting your visualization:
  • Parses correctly with --output human
  • Condensed view shows critical information only
  • Amounts and addresses are accurate
  • Labels are clear to non-technical users
  • Test fixture added and passing