commonMain.com.varabyte.truthish.failure.FailureStrategy.kt Maven / Gradle / Ivy

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package com.varabyte.truthish.failure

/**
 * A strategy for how an assertion failure should be handled.
 *
 * The most common strategy is to throw an exception, but a custom strategy can be registered with
 * a [Reportable] if needed.
 */
interface FailureStrategy {
    fun handle(report: Report)
}

internal class ReportError(val report: Report) : AssertionError(report.toString())

internal class MultipleReportsError(val reports: List, val summary: String? = null) : AssertionError(reports.buildErrorMessage(summary)) {
    companion object {
        private fun List.buildErrorMessage(summary: String?): String {
            val self = this
            return buildString {
                append("Grouped assertions had ${self.size} failure(s)\n")
                if (summary != null) {
                    appendLine("Summary: $summary")
                }
                appendLine()
                self.forEachIndexed { i, report ->
                    append("Failure ${i + 1}:\n")
                    append(report.toString())
                    appendLine()
                }
            }
        }
    }

    init {
        check(reports.isNotEmpty())
    }
}

/**
 * A strategy that will cause the test to fail immediately.
 */
class AssertionStrategy : FailureStrategy {
    override fun handle(report: Report) {
        throw ReportError(report)
    }
}

/**
 * A strategy that collects reports and defers them from asserting until we request it.
 *
 * This is useful for cases where multiple assertions are being made in a group, and you want to collect all the
 * failures at the same time, instead of dying on the first one you run into.
 */
class DeferredStrategy(private val summary: String? = null) : FailureStrategy {
    private val reports = mutableListOf()

    // e.g. JVM: at com.varabyte.truthish.AssertAllTest.assertAllCallstacksAreCorrect(AssertAllTest.kt:133)
    // exclude slashes so as not to clash with js node
    private val jvmCallstackRegex = Regex("\\s+at ([^ /]+\\.kt:\\d+[^ ]+)")

    // e.g. Node: at /Users/d9n/Code/1p/truthish/src/commonTest/kotlin/com/varabyte/truthish/AssertAllTest.kt:18:25
    // NOTE: There are also callstack lines like "at AssertAllTest.protoOf.assertAllCollectsMultipleErrors_tljnxt_k$ (/Users/d9n/Code/1p/truthish/src/commonTest/kotlin/com/varabyte/truthish/AssertAllTest.kt:14:13)"
    //       but I think we can skip over them and still get the user callstack line that we want, as user code will
    //       always(?) look like this.
    private val jsNodeCallstackRegex = Regex("\\s+at (/[^)]+)\\)?")

    // e.g. at 1 test.kexe 0x104adf41f kfun:com.varabyte.truthish.AssertAllTest#assertAllCallstacksAreCorrect(){} + 1847 (/Users/d9n/Code/1p/truthish/src/commonTest/kotlin/com/varabyte/truthish/AssertAllTest.kt:133:21)
    private val knCallstackRegex = Regex("\\s+at.+kfun:(.+)")

    // e.g. at protoOf.assertAllCallstacksAreCorrect_nyk2hi(/var/folders/5x/f_r3s2p53rx2l_lffc7m9nmw0000gn/T/_karma_webpack_413015/commons.js:29616)
    private val jsBrowserCallstackRegex = Regex("\\.js\\?")

    override fun handle(report: Report) {
        reports.add(report)

        val callstackLine =
            Throwable()
            .stackTraceToString()
            // Reject JS browser callstacks because they're mangled
            .takeUnless { jsBrowserCallstackRegex.containsMatchIn(it) }
            ?.split("\n")
            ?.drop(1) // Drop "java.lang.Throwable" line
            ?.asSequence()
            ?.mapNotNull { stackTraceLine ->
                jvmCallstackRegex.matchEntire(stackTraceLine)
                    ?: knCallstackRegex.matchEntire(stackTraceLine)
                    ?: jsNodeCallstackRegex.matchEntire(stackTraceLine)
            }
            ?.map { match -> match.groupValues[1] }
            ?.filterNot {
                it.startsWith("com.varabyte.truthish.failure.")
                        || it.startsWith("com.varabyte.truthish.subjects.")
                        || it.startsWith("kotlin.") // Kotlin/Native
            }
            ?.firstOrNull()

        if (callstackLine != null) {
            report.details.add(DetailsFor.AT to AnyStringifier(callstackLine))
        }
    }

    fun handleNow() {
        if (reports.isNotEmpty()) {
            throw MultipleReportsError(reports, summary)
        }
    }
}