Merge branch 'master' into custom-render-options

core/src/main/scala/pureconfig/error/ConfigReaderFailure.scala

@@ -55,6 +55,7 @@ object ConvertFailure {
 /**
  * A failure occurred because a list of files to load was empty.
  */
+@deprecated("`loadConfigFromFiles` won't return this failure anymore", "0.10.0")
 case object NoFilesToRead extends ConfigReaderFailure {
   def description = "The config files to load must not be empty."
   def location = None

core/src/main/scala/pureconfig/package.scala

@@ -276,27 +276,28 @@ package object pureconfig {
   }
 
   /**
-   * Loads `files` in order, allowing values in later files to backstop missing values from prior, and converts them into a `Config`.
+   * Loads `files` in order, allowing values in later files to backstop missing values from prior, and converts them
+   * into a `Config`.
    *
    * This is a convenience method which enables having default configuration which backstops local configuration.
    *
-   * Note: If an element of `files` references a file which doesn't exist or can't be read, it will silently be ignored.
+   * The behavior of the method if an element of `files` references a file which doesn't exist or can't be read is
+   * defined by the `failOnReadError` flag. With `failOnReadError = false`, such files will silently be ignored while
+   * otherwise they would yield a failure (a `Left` value).
    *
-   * @param files Files ordered in decreasing priority containing part or all of a `Config`. Must not be empty.
+   * @param files Files ordered in decreasing priority containing part or all of a `Config`
    */
-  def loadConfigFromFiles[Config](files: Traversable[Path])(implicit reader: Derivation[ConfigReader[Config]]): Either[ConfigReaderFailures, Config] = {
-    if (files.isEmpty) {
-      Left(ConfigReaderFailures(NoFilesToRead))
-    } else {
-      files
-        .map(parseFile)
-        .foldLeft[Either[ConfigReaderFailures, Seq[TypesafeConfig]]](Right(Seq())) {
-          case (c1, Left(failures)) if failures.toList.exists(_.isInstanceOf[CannotReadFile]) => c1
-          case (c1, c2) => ConfigConvert.combineResults(c1, c2)(_ :+ _)
-        }
-        .right.map(_.reduce(_.withFallback(_)).resolve)
-        .right.flatMap(loadConfig[Config])
-    }
+  def loadConfigFromFiles[Config](files: Traversable[Path], failOnReadError: Boolean = false)(implicit reader: Derivation[ConfigReader[Config]]): Either[ConfigReaderFailures, Config] = {
+    files.map(parseFile)
+      .map {
+        case Left(failures) if failures.toList.exists(_.isInstanceOf[CannotReadFile]) && !failOnReadError =>
+          Right(ConfigFactory.empty())
+        case conf => conf
+      }
+      .foldLeft[Either[ConfigReaderFailures, TypesafeConfig]](Right(ConfigFactory.empty())) {
+        case (c1, c2) => ConfigConvert.combineResults(c1, c2)(_.withFallback(_))
+      }
+      .right.flatMap { conf => loadConfig[Config](conf.resolve) }
   }
 
   /**

core/src/test/scala/pureconfig/ApiSuite.scala

@@ -155,18 +155,24 @@ class ApiSuite extends BaseSuite {
     loadConfigFromFiles[Conf](files) shouldBe Right(Conf(0.99F))
   }
 
-  it should "fail if the list of files is empty" in {
+  it should "use an empty config if the list of files is empty" in {
     case class Conf(f: Float)
     val files = Set.empty[Path]
-    loadConfigFromFiles[Conf](files) should failWithType[NoFilesToRead.type]
+    loadConfigFromFiles[Conf](files) should failWithType[KeyNotFound] // f is missing
   }
 
-  it should "ignore files that don't exist" in {
+  it should "ignore files that don't exist when failOnReadError is false" in {
     case class Conf(b: Boolean, d: Double)
     val files = listResourcesFromNames("/conf/loadConfigFromFiles/priority2.conf") :+ nonExistingPath
     loadConfigFromFiles[Conf](files) shouldBe Right(Conf(false, 0.001D))
   }
 
+  it should "fail if any of the files doesn't exist and failOnReadError is true" in {
+    case class Conf(f: Float)
+    val files = listResourcesFromNames("/conf/loadConfigFromFiles/priority2.conf") :+ nonExistingPath
+    loadConfigFromFiles[Conf](files, failOnReadError = true) should failWithType[CannotReadFile]
+  }
+
   "loadConfigWithFallback" should "fallback if no config keys are found" in {
     case class Conf(f: Float, o: Option[Int], d: Double)
     val priority1Conf = ConfigFactory.load("conf/loadConfigFromFiles/priority1.conf")