Analyze assembly error - Reproduction of #528 and #2650

Reprodcution of issues
* #528
* #2650

integration/feature/assembly/repo/build.sc

@@ -0,0 +1,21 @@
+import mill._, scalalib._
+
+trait Setup extends ScalaModule {
+  def scalaVersion = "2.13.11"
+  def ivyDeps = Agg(
+    ivy"com.lihaoyi::scalatags:0.8.2",
+    ivy"com.lihaoyi::mainargs:0.4.0",
+    ivy"org.apache.avro:avro:1.11.1",
+    ivy"dev.zio::zio:2.0.15",
+    ivy"org.typelevel::cats-core:2.9.0",
+    ivy"org.apache.spark::spark-core:3.4.0",
+    ivy"dev.zio::zio-metrics-connectors:2.0.8",
+    ivy"dev.zio::zio-http:3.0.0-RC2"
+  )
+}
+
+object foo extends Setup {
+  override def prependShellScript: T[String] = ""
+}
+
+object bar extends Setup

integration/feature/assembly/repo/foo/src/Main.scala

@@ -0,0 +1,17 @@
+package ultra
+
+import scalatags.Text.all._
+import mainargs.{main, ParserForMethods}
+
+object Main {
+  def generateHtml(text: String) = {
+    h1(text).toString
+  }
+
+  @main
+  def main(text: String) = {
+    println(generateHtml(text))
+  }
+
+  def main(args: Array[String]): Unit = ParserForMethods(this).runOrExit(args)
+}

integration/feature/assembly/test/src/AssemblyTests.scala

@@ -0,0 +1,41 @@
+package mill.integration.local
+
+import mill.integration.IntegrationTestSuite
+import mill.util.Jvm
+import utest._
+
+// Ensure the assembly is runnable, even if we have assembled lots of dependencies into it
+// Reproduction of issues:
+// - https://github.com/com-lihaoyi/mill/issues/528
+// - https://github.com/com-lihaoyi/mill/issues/2650
+
+object AssemblyTests extends IntegrationTestSuite {
+  def tests: Tests = Tests {
+    test("Assembly") {
+      test("without-prependShellScript") {
+        val workspacePath = initWorkspace()
+        assert(eval("foo.assembly"))
+        val assemblyFile = workspacePath / "out" / "foo" / "assembly.dest" / "out.jar"
+        assert(os.exists(assemblyFile))
+        println(s"File size: ${os.stat(assemblyFile).size}")
+        Jvm.runSubprocess(
+          commandArgs = Seq(Jvm.javaExe, "-jar", assemblyFile.toString(), "--text", "tutu"),
+          envArgs = Map.empty[String, String],
+          workingDir = workspacePath
+        )
+      }
+      test("with-prependShellScript") {
+        val workspacePath = initWorkspace()
+        assert(eval("bar.assembly"))
+        val assemblyFile = workspacePath / "out" / "bar" / "assembly.dest" / "out.jar"
+        assert(os.exists(assemblyFile))
+        println(s"File size: ${os.stat(assemblyFile).size}")
+        Jvm.runSubprocess(
+          commandArgs = Seq(Jvm.javaExe, "-jar", assemblyFile.toString(), "--text", "tutu"),
+          envArgs = Map.empty[String, String],
+          workingDir = workspacePath
+        )
+      }
+    }
+  }
+}