fix ExpressionTest#verifyImports test compile error introduced in #14263

[philwalk]

The -e (eval) expression in dotty.tools.scripting.ExpressionTest#verifyImports fails to compile, but the test passes anyway because of a missing assertion.

This PR corrects the expression so that it compiles, and it asserts that the expression must print an integer to STDOUT, so that the test will fail if the -e <expression> implementation fails.

The compile error is mentioned in #14332

[michelou]

First 2 remarks about the code in ExpressionTest.scala :

1. On line 30, the 's' prefix is not need in front of the triple quoted string.
2. On line 39, the variable cmd is unused.

Then 2 questions about the usage of bashCommand in ExpressionTest.scala :

1. In file BashScriptTests.scala bashCommand makes use of ScriptTestEnv.scalaPath; why not use the same mechanism here ?
   E.g., val (_, _, stdout, stderr) = bashCommand(s"""$scalaPath -e '$expression'""").
2. In variable expressionLines (line 28) I read Paths.get("\""."\""); for me the code only works if I write Paths.get("\"."\") (see console output below). Did you check the console output starting with bashCmd ?

Finally, adding assert(success) (line 36) is good !

PS. Here is the output I get with my local copy of file ExpressionTest.scala (Win11 Pro, Scala 3.1.0):

Y:\dotty>"%SCALA3_HOME%\bin\scalac" -cp "%REPO_DIR%\junit\junit\4.13.2\junit-4.13.2.jar;compiler\target\scala-3.1.2-RC1\test-classes" compiler\test\dotty\tools\scripting\ExpressionTest.scala -d c:\temp\

Y:\dotty>"%SCALA3_HOME%\bin\scala" -cp "%REPO_DIR%\junit\junit\4.13.2\junit-4.13.2.jar;c:\temp;compiler\target\scala-3.1.2-RC1\classes;compiler\target\scala-3.1.2-RC1\test-classes" dotty.tools.scripting.ExpressionTest
working directory is [Y:/dotty]

=== verifyCommandLineExpression ===
===> verify -e <expression> is properly handled by `dist/bin/scala`
bashCmd: C:/windows/system32/bash.exe -c "/mnt/c/Users/michelou/workspace-perso/dotty-examples/dotty/dist/target/pack/bin/scala -e 'println(3*3)'"
scalacPath: Y:/dotty/dist/target/pack/bin/scalac
JAVA_HOME : C:\opt\jdk-temurin-1.8.0u322-b06
SCALA_HOME : Y:/dotty/dist/target/pack
PATH : dist/target/pack/bin;C:/opt/jdk-temurin-1.8.0u322-b06/bin;[...]
SHELLOPTS : igncr:braceexpand:hashall:ignoreeof:monitor:vi
stdout: 9
stderr:

=== verifyImports ===
bashCmd: C:/windows/system32/bash.exe -c "/mnt/c/Users/michelou/workspace-perso/dotty-examples/dotty/dist/target/pack/bin/scala -e 'import java.nio.file.Paths;println(Paths.get("\"."\").toFile.listFiles.toList.filter(_.isDirectory).size)'"
stdout: 19
stderr:

Note: I appended the following code to file ExpressionTest.scala to get the above output :

object ExpressionTest:

  def main(args: Array[String]): Unit =
    val tests = new ExpressionTest
    println("\n=== verifyCommandLineExpression ===")
    tests.verifyCommandLineExpression
    println("\n=== verifyImports ===")
    tests.verifyImports

[michelou]

@philwalk 3 more suggestions for file ExpressionTest.scala :

1. line 28 : remove empty line in function verifyImports
2. line 31 : use scala.util.Properties.userDir instead of dotty.tools.dotc.config.Properties.userDir.
3. line 46 : remove opening and closing braces (indentation is enough)

Otherwise, LGTM.

[philwalk]

@michelou - thanks for the detailed feedback, that helps!

It turns out that changing the bash command to s"""$scalaPath -e '$expression'""" breaks the test on my system.
I spent quite some time trying to figure out exactly what was happening, but in any event, it's related to the expression having double quotes, which are consumed when bash interpolates. To avoid the problem, I removed the double quotes altogether, rather than trying to escape them.

I just noticed the code still has a residual unused 's' prefix (this time it's on line 32!).

[philwalk]

I'll do another push with all suggested changes after the workflow dies down a bit later this evening.

[michelou]

I'll do another push with all suggested changes after the workflow dies down a bit later this evening.

👍

[philwalk]

@michelou -
I'm inclined to add your suggested main method at the bottom:

object ExpressionTest:

  def main(args: Array[String]): Unit =
    val tests = new ExpressionTest
    println("\n=== verifyCommandLineExpression ===")
    tests.verifyCommandLineExpression
    println("\n=== verifyImports ===")
    tests.verifyImports

[michelou]

@michelou - I'm inclined to add your suggested main method at the bottom:

object ExpressionTest:
  //...

It's a small (local) addition I also have in BashScriptTests; it helps me to quickly experiment with the bash.exe arguments on Windows (as illustrated in the above postscriptum).