Introduce Throwable.toStringWithTrace

#KT-37603

libraries/stdlib/common/src/kotlin/ExceptionsH.kt

@@ -118,6 +118,17 @@ internal class KotlinNothingValueException : RuntimeException {
 }
 
 
+/**
+ * Returns the detailed description of this throwable with its stack trace.
+ *
+ * The detailed description includes:
+ * - the short description (see [Throwable.toString]) of this throwable;
+ * - the complete stack trace;
+ * - detailed descriptions of the exceptions that were [suppressed][suppressedExceptions] in order to deliver this exception;
+ * - the detailed description of each throwable in the [Throwable.cause] chain.
+ */
+@SinceKotlin("1.4")
+public expect fun Throwable.toStringWithTrace(): String
 /**
  * When supported by the platform, adds the specified exception to the list of exceptions that were
  * suppressed in order to deliver this exception.

libraries/stdlib/js/src/kotlin/throwableExtensions.kt

@@ -5,6 +5,18 @@
 
 package kotlin
 
+/**
+ * Returns the detailed description of this throwable with its stack trace.
+ *
+ * The detailed description includes:
+ * - the short description (see [Throwable.toString]) of this throwable;
+ * - the complete stack trace;
+ * - detailed descriptions of the exceptions that were [suppressed][suppressedExceptions] in order to deliver this exception;
+ * - the detailed description of each throwable in the [Throwable.cause] chain.
+ */
+@SinceKotlin("1.4")
+public actual fun Throwable.toStringWithTrace(): String = buildString { dumpStackTraceTo("", "", this) }
+
 /**
  * Adds the specified exception to the list of exceptions that were
  * suppressed in order to deliver this exception.
@@ -29,3 +41,42 @@ public actual val Throwable.suppressedExceptions: List<Throwable>
     get() {
         return this.asDynamic()._suppressed?.unsafeCast<List<Throwable>>() ?: emptyList()
     }
+
+
+private fun Throwable.dumpStackTraceTo(indent: String, qualifier: String, target: StringBuilder) {
+    this.dumpSelfTrace(indent, qualifier, target)
+
+    var cause = this.cause
+    while (cause != null) {
+        // TODO: should skip common stack frames
+        cause.dumpSelfTrace(indent, "Caused by: ", target)
+        cause = cause.cause
+    }
+}
+
+private fun Throwable.dumpSelfTrace(indent: String, qualifier: String, target: StringBuilder) {
+    target.append(indent).append(qualifier)
+    val stack = this.asDynamic().stack as String?
+    if (stack != null) {
+        if (indent.isNotEmpty()) {
+            // indent stack, but avoid indenting exception message lines
+            val messageLines = 1 + (message?.count { c -> c == '\n' } ?: 0)
+            stack.lineSequence().forEachIndexed { index: Int, line: String ->
+                if (index >= messageLines) target.append(indent)
+                target.append(line).append("\n")
+            }
+        } else {
+            target.append(stack).append("\n")
+        }
+    } else {
+        target.append(this.toString()).append("\n")
+    }
+
+    val suppressed = suppressedExceptions
+    if (suppressed.isNotEmpty()) {
+        val suppressedIndent = indent + '\t'
+        for (s in suppressed) {
+            s.dumpStackTraceTo(suppressedIndent, "Suppressed: ", target)
+        }
+    }
+}

libraries/stdlib/jvm/src/kotlin/util/Exceptions.kt

@@ -10,24 +10,25 @@ package kotlin
 
 import java.io.PrintStream
 import java.io.PrintWriter
+import java.io.StringWriter
 import kotlin.internal.*
 
 /**
- * Prints the stack trace of this throwable to the standard output.
+ * Prints the [detailed description][Throwable.toStringWithTrace] of this throwable to the standard error output.
  */
 @Suppress("EXTENSION_SHADOWED_BY_MEMBER") // to be used when no member available
 @kotlin.internal.InlineOnly
 public inline fun Throwable.printStackTrace(): Unit = (this as java.lang.Throwable).printStackTrace()
 
 /**
- * Prints the stack trace of this throwable to the specified [writer].
+ * Prints the [detailed description][Throwable.toStringWithTrace] of this throwable to the specified [writer].
  */
 @Suppress("EXTENSION_SHADOWED_BY_MEMBER") // to be used when no member available
 @kotlin.internal.InlineOnly
 public inline fun Throwable.printStackTrace(writer: PrintWriter): Unit = (this as java.lang.Throwable).printStackTrace(writer)
 
 /**
- * Prints the stack trace of this throwable to the specified [stream].
+ * Prints the [detailed description][Throwable.toStringWithTrace] of this throwable to the specified [stream].
  */
 @Suppress("EXTENSION_SHADOWED_BY_MEMBER") // to be used when no member available
 @kotlin.internal.InlineOnly
@@ -41,6 +42,24 @@ public inline fun Throwable.printStackTrace(stream: PrintStream): Unit = (this a
 public val Throwable.stackTrace: Array<StackTraceElement>
     get() = (this as java.lang.Throwable).stackTrace!!
 
+/**
+ * Returns the detailed description of this throwable with its stack trace.
+ *
+ * The detailed description includes:
+ * - the short description (see [Throwable.toString]) of this throwable;
+ * - the complete stack trace;
+ * - detailed descriptions of the exceptions that were [suppressed][suppressedExceptions] in order to deliver this exception;
+ * - the detailed description of each throwable in the [Throwable.cause] chain.
+ */
+@SinceKotlin("1.4")
+public actual fun Throwable.toStringWithTrace(): String {
+    val sw = StringWriter()
+    val pw = PrintWriter(sw)
+    printStackTrace(pw)
+    pw.flush()
+    return sw.toString()
+}
+
 /**
  * When supported by the platform, adds the specified exception to the list of exceptions that were
  * suppressed in order to deliver this exception.

libraries/stdlib/jvm/test/ExceptionJVMTest.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -7,6 +7,7 @@ package test.exceptions
 
 import kotlin.test.*
 import test.collections.assertArrayNotSameButEquals
+import test.testOnJvm7AndAbove
 
 import java.io.PrintWriter
 import java.io.*
@@ -17,11 +18,13 @@ class ExceptionJVMTest {
     @Test fun printStackTraceOnRuntimeException() {
         assertPrintStackTrace(RuntimeException("Crikey!"))
         assertPrintStackTraceStream(RuntimeException("Crikey2"))
+        assertToStringWithTrace(RuntimeException("ToString"))
     }
 
     @Test fun printStackTraceOnError() {
         assertPrintStackTrace(Error("Oh dear"))
         assertPrintStackTraceStream(Error("Oh dear2"))
+        assertToStringWithTrace(Error("ToString"))
     }
 
 
@@ -49,6 +52,11 @@ class ExceptionJVMTest {
         comparePrintedThrowableResult(t, content)
     }
 
+    fun assertToStringWithTrace(t: Throwable) {
+        val content = t.toStringWithTrace()
+        comparePrintedThrowableResult(t, content)
+    }
+
     private fun comparePrintedThrowableResult(throwable: Throwable, printedThrowable: CharSequence) {
         val stackTrace = throwable.stackTrace
         val lines = printedThrowable.lines()
@@ -72,4 +80,16 @@ class ExceptionJVMTest {
 
         e1.addSuppressed(e2)
     }
+
+    @Test fun circularCauseStackTrace() {
+        val e1 = Exception("cause")
+        val e2 = Error("induced", e1)
+        e1.initCause(e2)
+        assertSame(e1, e2.cause)
+        assertSame(e2, e1.cause)
+        testOnJvm7AndAbove {
+            val trace = e2.toStringWithTrace()
+            assertTrue("CIRCULAR REFERENCE" in trace, trace)
+        }
+    }
 }

libraries/stdlib/jvm/test/testUtilsJVM.kt

@@ -26,6 +26,11 @@ internal actual inline fun testOnNonJvm6And7(f: () -> Unit) {
         f()
     }
 }
+internal inline fun testOnJvm7AndAbove(f: () -> Unit) {
+    if (!isJava6) {
+        f()
+    }
+}
 public actual fun testOnJvm(action: () -> Unit) = action()
 public actual fun testOnJs(action: () -> Unit) {}
 

libraries/stdlib/test/ExceptionTest.kt

@@ -87,4 +87,47 @@ class ExceptionTest {
         }
     }
 
+    @Test
+    fun exceptionDetailedTrace() {
+        fun root(): Nothing = throw IllegalStateException("Root cause\nDetails: root")
+
+        fun suppressedError(id: Int): Throwable = UnsupportedOperationException("Side error\nId: $id")
+
+        fun induced(): Nothing {
+            try {
+                root()
+            } catch (e: Throwable) {
+                e.addSuppressed(suppressedError(1))
+                throw RuntimeException("Induced", e)
+            }
+        }
+
+        val e = try {
+            induced()
+        } catch (e: Throwable) {
+            e.apply { addSuppressed(suppressedError(2)) }
+        }
+
+        val topLevelTrace = e.toStringWithTrace()
+        fun assertInTrace(value: Any) {
+            if (value.toString() !in topLevelTrace) {
+                fail("Expected top level trace: $topLevelTrace\n\nto contain: $value")
+            }
+        }
+
+        assertInTrace(e)
+
+        val cause = assertNotNull(e.cause, "Should have cause")
+        assertInTrace(cause)
+
+        if (supportsSuppressedExceptions) {
+            val topLevelSuppressed = e.suppressedExceptions.single()
+            assertInTrace(topLevelSuppressed)
+            val causeSuppressed = cause.suppressedExceptions.single()
+            assertInTrace(causeSuppressed)
+        }
+
+//        fail(topLevelTrace) // to dump the entire trace
+    }
+
 }