Default to the run sub-command when --main-class and -classpath have been passed (but there were no explicit inputs)

Author: Gedochao

modules/cli/src/main/scala/scala/cli/commands/Default.scala

@@ -34,7 +34,8 @@ class Default(
       {
         val shouldDefaultToRun =
           args.remaining.nonEmpty || options.shared.snippet.executeScript.nonEmpty ||
-          options.shared.snippet.executeScala.nonEmpty || options.shared.snippet.executeJava.nonEmpty
+          options.shared.snippet.executeScala.nonEmpty || options.shared.snippet.executeJava.nonEmpty ||
+          (options.shared.extraJarsAndClasspath.nonEmpty && options.sharedRun.mainClass.mainClass.nonEmpty)
         if shouldDefaultToRun then RunOptions.parser else ReplOptions.parser
       }.parse(rawArgs) match
         case Left(e)                              => error(e)

modules/integration/src/test/scala/scala/cli/integration/DefaultTests.scala

@@ -6,7 +6,7 @@ class DefaultTests extends ScalaCliSuite {
   test("running scala-cli with no args should default to repl") {
     TestInputs.empty.fromRoot { root =>
       val res = os.proc(TestUtil.cli, "--repl-dry-run").call(cwd = root, mergeErrIntoOut = true)
-      expect(res.out.trim() == "Dry run, not running REPL.")
+      expect(res.out.trim() == replDryRunOutput)
     }
   }
   test("running scala-cli with no args should not accept run-only options") {
@@ -94,11 +94,66 @@ class DefaultTests extends ScalaCliSuite {
     }
   }
 
+  test("default to the run sub-command if -classpath and --main-class are passed") {
+    val expectedOutput = "Hello"
+    val mainClassName = "Main"
+    TestInputs(
+      os.rel / s"$mainClassName.scala" -> s"""object $mainClassName extends App { println("$expectedOutput") }"""
+    ).fromRoot { (root: os.Path) =>
+      val compilationOutputDir = os.rel / "compilationOutput"
+      // first, precompile to an explicitly specified output directory with -d
+      os.proc(
+        TestUtil.cli,
+        ".",
+        "-d",
+        compilationOutputDir
+      ).call(cwd = root)
+
+      // next, run while relying on the pre-compiled class instead of passing inputs
+      val runRes = os.proc(
+        TestUtil.cli,
+        "--main-class",
+        mainClassName,
+        "-classpath",
+        (os.rel / compilationOutputDir).toString
+      ).call(cwd = root)
+      expect(runRes.out.trim == expectedOutput)
+    }
+  }
+
+  test("default to the repl sub-command if -classpath is passed, but --main-class isn't") {
+    val expectedOutput = "Hello"
+    val mainClassName = "Main"
+    TestInputs(
+      os.rel / s"$mainClassName.scala" -> s"""object $mainClassName extends App { println("$expectedOutput") }"""
+    ).fromRoot { (root: os.Path) =>
+      val compilationOutputDir = os.rel / "compilationOutput"
+      // first, precompile to an explicitly specified output directory with -d
+      os.proc(
+        TestUtil.cli,
+        ".",
+        "-d",
+        compilationOutputDir
+      ).call(cwd = root)
+
+      // next, run the repl while relying on the pre-compiled classes
+      val runRes = os.proc(
+        TestUtil.cli,
+        "--repl-dry-run",
+        "-classpath",
+        (os.rel / compilationOutputDir).toString
+      ).call(cwd = root, mergeErrIntoOut = true)
+      expect(runRes.out.trim == replDryRunOutput)
+    }
+  }
+
   private def unrecognizedArgMessage(argName: String) =
     s"""
        |Unrecognized argument: $argName
        |
        |To list all available options, run
        |  ${Console.BOLD}${TestUtil.detectCliPath} --help${Console.RESET}
        |""".stripMargin.trim
+
+  private lazy val replDryRunOutput = "Dry run, not running REPL."
 }