Validate classpath.

src/main/kotlin/com/beust/kobalt/internal/JvmCompilerPlugin.kt

@@ -110,6 +110,14 @@ abstract public class JvmCompilerPlugin @Inject constructor(
             lp(project, "No resources to copy for ${sourceSet}")
         }
     }
+
+    protected fun validateClasspath(cp: List<String>) {
+        cp.forEach {
+            if (! File(it).exists()) {
+                throw KobaltException("Couldn't find $it")
+            }
+        }
+    }
 }
 
 

src/main/kotlin/com/beust/kobalt/plugin/java/JavaPlugin.kt

@@ -51,8 +51,10 @@ public class JavaPlugin @Inject constructor(
                 javac!!.absolutePath,
                 "-d", outputDirectory.absolutePath)
         if (cpList.size() > 0) {
+            val stringClasspath = cpList.map { it.jarFile.get().absolutePath }
+            validateClasspath(stringClasspath)
             args.add("-classpath")
-            args.add(cpList.map { it.jarFile.get().absolutePath }.join(File.pathSeparator))
+            args.add(stringClasspath.join(File.pathSeparator))
         }
         args.addAll(sourceFiles)
 

src/main/kotlin/com/beust/kobalt/plugin/kotlin/KotlinCompiler.kt

@@ -48,6 +48,8 @@ class KotlinCompiler @Inject constructor(override val localRepo : LocalRepo,
         classpathList.addAll(otherClasspath)
         classpathList.addAll(calculateClasspath(compileDependencies).map { it.id })
 
+        validateClasspath(classpathList)
+
         log(2, "Compiling ${source.size()} files with classpath:\n  " + classpathList.join("\n  "))
         K2JVMCompiler.main(arrayOf(
                 "-d", output,