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Module: pattern-support

pattern-support connects the standalone pattern-value module to the core generation engine. It is what turns "this string schema has a pattern" into both a valid example value (a string matching the regex) and a negative test case (a string that does not match).

Most users never touch this module: distribution-bundle registers it by default, so the CLI and Gradle plugin have pattern-aware behavior out of the box. Wire it manually only when embedding core directly.

What it contributes

Contribution Type Effect
Schema value provider id pattern PatternValueProvider from pattern-value Generates valid example values for string schemas with a pattern
Negative rule InvalidPatternSchemaValidationRule (rule name "Invalid Pattern") Generates a non-matching string per patterned schema — see the rules catalog
Settings extractor PatternModuleSettingsExtractor (settings key patternGeneration) Parses the testGenerationSettings.patternGeneration block into PatternGenerationOptions

Depends on / used by

  • Depends on: core (module and rule SPIs) and pattern-value (the actual regex generation)
  • Used by: distribution-bundle — DistributionDefaults.modules() registers PatternSupportModule, DistributionDefaults.extractors() registers the settings extractor, and the default provider order inserts pattern before plain-string

Installation

Only needed for direct embedding — CLI and Gradle plugin users get it transitively:

dependencies {
    implementation("art.galushko.openapi.testgen:pattern-support:<version>")
}

Key types

  • PatternSupportModule — a TestGenerationModule with id pattern-support. Takes PatternGenerationOptions as an optional constructor argument; one PatternValueGenerator is shared by the value provider and the rule, so both honor the same options.
  • PatternModuleSettingsExtractor — a Kotlin object implementing ModuleSettingsExtractor. Its settingsKey is patternGeneration; a non-map value under that key fails fast with a ConfigurationException.
  • InvalidPatternSchemaValidationRule — a SimpleSchemaValidationRule that applies to string schemas with a non-null pattern. When the underlying library cannot produce a non-matching string (see pattern-value limitations), the rule logs and skips that schema instead of failing.

Configure pattern generation

Configuration is owned by Distribution settings — patternGeneration; the options themselves (defaultMinLength, spaceChars, anyPrintableChars) are documented in pattern-value. Example:

testGenerationSettings:
    patternGeneration:
        defaultMinLength: 10

Wire the module when embedding core

The settings extractor runs during option resolution and stores the parsed options under the module settings key; the module is then constructed with those options:

import art.galushko.openapi.testgen.config.TestGenerationEngine
import art.galushko.openapi.testgen.config.TestGeneratorExecutionOptionsFactory
import art.galushko.openapi.testgen.config.TestGeneratorOverrides
import art.galushko.openapi.testgen.pattern.support.PatternModuleSettingsExtractor
import art.galushko.openapi.testgen.pattern.support.PatternSupportModule
import art.galushko.openapi.testgen.pattern.value.PatternGenerationOptions
import java.nio.file.Path

val options = TestGeneratorExecutionOptionsFactory.fromConfig(
    config = null,
    overrides = TestGeneratorOverrides(
        specFile = "openapi.yaml",
        outputDir = Path.of("build/generated"),
        generatorId = "test-suite-writer",
        testGenerationSettings = mapOf(
            "patternGeneration" to mapOf("defaultMinLength" to 10),
        ),
    ),
    moduleExtractors = listOf(PatternModuleSettingsExtractor),
)

val patternOptions = options.moduleSettings
    .get<PatternGenerationOptions>(PatternModuleSettingsExtractor.SETTINGS_KEY)
    ?: PatternGenerationOptions()

val report = TestGenerationEngine.generateReport(
    options,
    modules = listOf(PatternSupportModule(patternOptions)),
)

This mirrors exactly what TestGenerationRunner.withDefaults() does in distribution-bundle.

Testing

./gradlew :pattern-support:test
./gradlew :pattern-support:check

API reference