Behat Table Comparison

The Behat Table Comparison library provides an equality assertion for comparing Behat TableNode tables.

Installation & Usage

Install the library via Composer:

composer require --dev traviscarden/behat-table-comparison

Then use the TableEqualityAssertion class in your FeatureContext class:

<?php

use Behat\Behat\Context\Context;
use Behat\Gherkin\Node\TableNode;
use TravisCarden\BehatTableComparison\TableEqualityAssertion;

class FeatureContext implements Context
{

    /**
     * @Then I should include the following characters in the Company of the Ring
     */
    public function iShouldIncludeTheFollowingCharactersInTheCompanyOfTheRing(TableNode $expected)
    {
        // Get the data from the application and create a table from it.
        $application_data = [
            ['name', 'race'],  // Header row (required when using expectHeader(...)
            ['Frodo Baggins', 'Hobbit'],
            ['Samwise "Sam" Gamgee', 'Hobbit'],
            ['Saruman the White', 'Wizard'],
            ['Legolas', 'Elf'],
            ['Gimli', 'Dwarf'],
            ['Aragorn (Strider)', 'Man'],
            ['Boromir', 'Man'],
            ['Meriadoc "Merry" Brandybuck', 'Hobbit'],
            ['Peregrin "Pippin" Took', 'Hobbit'],
        ];
        $actual = new TableNode($application_data);

        // Build and execute assertion.
        (new TableEqualityAssertion($expected, $actual))
            ->expectHeader(['name', 'race'])
            ->ignoreRowOrder()
            ->setMissingRowsLabel('Missing characters')
            ->setUnexpectedRowsLabel('Unexpected characters')
            ->setDuplicateRowsLabel('Duplicate characters')
            ->assert();
    }

}

Output is like the following:

Understanding Headers and Terminology

When using expectHeader(...), it's important to understand the asymmetrical design:

• Specified header: The header you declare by calling expectHeader(...). This is what the columns should be.
• Expected table: The table you provide as the first argument to TableEqualityAssertion (your test specification). Its first row must match the specified header and is stripped before comparison.
• Actual table: The table you provide as the second argument to TableEqualityAssertion (the application's real output). It is compared as-is with no header validation or stripping.

This design is intentional: test specifications typically include headers (e.g., from Gherkin), while application-generated output often does not.

Error Message Specification

When tables are unequal, the assertion throws UnequalTablesException with a detailed diagnostic message. The integer error code, available via getCode(), identifies the category of failure:

Constant	When thrown
UnequalTablesException::HEADER_MISMATCH	The header row does not match the expected header.
UnequalTablesException::CONTENT_MISMATCH	Rows are missing, unexpected, or duplicated.
UnequalTablesException::ROW_ORDER_MISMATCH	The same rows are present but in a different order.
UnequalTablesException::STRUCTURAL_ERROR	A structural failure occurred processing a table; see getPrevious().

Consumers should use the named constants rather than bare integers. For example:

try {
    (new TableEqualityAssertion($expected, $actual))->assert();
} catch (UnequalTablesException $e) {
    match ($e->getCode()) {
        UnequalTablesException::HEADER_MISMATCH    => /* handle header issue */,
        UnequalTablesException::ROW_ORDER_MISMATCH => /* handle order issue */,
        default                                    => /* handle content issue */,
    };
}

For a complete list of stable/public guarantees, see Contract Surface.

Difference sections

• --- Missing rows: Rows present in expected but not in actual.
• +++ Unexpected rows: Rows present in actual but not in expected.
• *** Duplicate rows: Rows present on both sides with different multiplicity, shown as (appears N time/times, expected M).

Row-order diagnostics

When row order is respected and rows are out of order:

• *** Row order mismatch is shown.
• Per-row diagnostics are listed as ... should be at position X, found at Y.
• Full order context is appended under:
  • Expected order
  • Actual order

When row content differs while respecting row order, semantic missing/unexpected/duplicate sections are shown first, then full expected/actual order tables.

Header mismatch diagnostics

When expectHeader(...) is used and the expected table's first row does not match the specified header:

• --- Expected header: The header specification passed to expectHeader(...)
• +++ Given header: The expected table's first row (the test specification header that was provided)

Label customization

All user-facing section labels are configurable via defaults plus getter/setter pairs:

• Missing rows
• Unexpected rows
• Duplicate rows
• Row order mismatch
• Expected header
• Given header
• Expected order subheading
• Actual order subheading

Examples

See examples/bootstrap/FeatureContext.php and examples/features/examples.feature for more examples.

Contribution

All contributions are welcome according to normal open source practice.