How to read files from test resources with scalatest? [duplicate] - scala

Question

I have a folder structure like below:
- main
-- java
-- resources
-- scalaresources
--- commandFiles
and in that folders I have my files that I have to read.
Here is the code:
def readData(runtype: String, snmphost: String, comstring: String, specificType: String): Unit = {
val realOrInvFile = "/commandFiles/snmpcmds." +runtype.trim // these files are under commandFiles folder, which I have to read.
try {
if (specificType.equalsIgnoreCase("Cisco")) {
val specificDeviceFile: String = "/commandFiles/snmpcmds."+runtype.trim+ ".cisco"
val realOrInvCmdsList = scala.io.Source.fromFile(realOrInvFile).getLines().toList.filterNot(line => line.startsWith("#")).map{
//some code
}
val specificCmdsList = scala.io.Source.fromFile(specificDeviceFile).getLines().toList.filterNot(line => line.startsWith("#")).map{
//some code
}
}
} catch {
case e: Exception => e.printStackTrace
}
}
}

Answer 1

Resources in Scala work exactly as they do in Java.
It is best to follow the Java best practices and put all resources in src/main/resources and src/test/resources.
Example folder structure:
testing_styles/
├── build.sbt
├── src
│   └── main
│   ├── resources
│   │   └── readme.txt
Scala 2.12.x && 2.13.x reading a resource
To read resources the object Source provides the method fromResource.
import scala.io.Source
val readmeText : Iterator[String] = Source.fromResource("readme.txt").getLines
reading resources prior 2.12 (still my favourite due to jar compatibility)
To read resources you can use getClass.getResource and getClass.getResourceAsStream .
val stream: InputStream = getClass.getResourceAsStream("/readme.txt")
val lines: Iterator[String] = scala.io.Source.fromInputStream( stream ).getLines
nicer error feedback (2.12.x && 2.13.x)
To avoid undebuggable Java NPEs, consider:
import scala.util.Try
import scala.io.Source
import java.io.FileNotFoundException
object Example {
def readResourceWithNiceError(resourcePath: String): Try[Iterator[String]] =
Try(Source.fromResource(resourcePath).getLines)
.recover(throw new FileNotFoundException(resourcePath))
}
good to know
Keep in mind that getResourceAsStream also works fine when the resources are part of a jar, getResource, which returns a URL which is often used to create a file can lead to problems there.
in Production
In production code I suggest to make sure that the source is closed again.

Answer 2

For Scala >= 2.12, use Source.fromResource:
scala.io.Source.fromResource("located_in_resouces.any")

Answer 3

One-liner solution for Scala >= 2.12
val source_html = Source.fromResource("file.html").mkString
Important taken from comments (thanks to #anentropic): with Source.fromResource you do not put the initial forward slash.

Answer 4

import scala.io.Source
object Demo {
def main(args: Array[String]): Unit = {
val ipfileStream = getClass.getResourceAsStream("/folder/a-words.txt")
val readlines = Source.fromInputStream(ipfileStream).getLines
readlines.foreach(readlines => println(readlines))
}
}

Answer 5

The required file can be accessed as below from resource folder in scala
val file = scala.io.Source.fromFile(s"src/main/resources/app.config").getLines().mkString

Answer 6

For Scala 2.11, if getLines doesn't do exactly what you want you can also copy the a file out of the jar to the local file system.
Here's a snippit that reads a binary google .p12 format API key from /resources, writes it to /tmp, and then uses the file path string as an input to a spark-google-spreadsheets write.
In the world of sbt-native-packager and sbt-assembly, copying to local is also useful with scalatest binary file tests. Just pop them out of resources to local, run the tests, and then delete.
import java.io.{File, FileOutputStream}
import java.nio.file.{Files, Paths}
def resourceToLocal(resourcePath: String) = {
val outPath = "/tmp/" + resourcePath
if (!Files.exists(Paths.get(outPath))) {
val resourceFileStream = getClass.getResourceAsStream(s"/${resourcePath}")
val fos = new FileOutputStream(outPath)
fos.write(
Stream.continually(resourceFileStream.read).takeWhile(-1 !=).map(_.toByte).toArray
)
fos.close()
}
outPath
}
val filePathFromResourcesDirectory = "google-docs-key.p12"
val serviceAccountId = "[something]#drive-integration-[something].iam.gserviceaccount.com"
val googleSheetId = "1nC8Y3a8cvtXhhrpZCNAsP4MBHRm5Uee4xX-rCW3CW_4"
val tabName = "Favorite Cities"
import spark.implicits
val df = Seq(("Brooklyn", "New York"),
("New York City", "New York"),
("San Francisco", "California")).
toDF("City", "State")
df.write.
format("com.github.potix2.spark.google.spreadsheets").
option("serviceAccountId", serviceAccountId).
option("credentialPath", resourceToLocal(filePathFromResourcesDirectory)).
save(s"${googleSheetId}/${tabName}")

Answer 7

The "resources" folder must be under the source root. if using intellj check for the blue folder in the project folders on the left side. eg AppName/src/main/scala or Project/scala/../main/ etc.
If using val stream: InputStream = getClass.getResourceAsStream("/readme.txt") don't forget the "/" (forward slash), given readme.txt is the file inside resources