Show error window if no test source root were found (#657)

Author: nikitavlaev

utbot-intellij/src/main/kotlin/org/utbot/intellij/plugin/generator/UtTestsDialogProcessor.kt

@@ -54,6 +54,7 @@ import org.utbot.common.filterWhen
 import org.utbot.engine.util.mockListeners.ForceStaticMockListener
 import org.utbot.framework.plugin.api.testFlow
 import org.utbot.intellij.plugin.settings.Settings
+import org.utbot.intellij.plugin.ui.utils.suitableTestSourceRoots
 import org.utbot.intellij.plugin.util.isAbstract
 import kotlin.reflect.KClass
 import kotlin.reflect.full.functions
@@ -89,6 +90,15 @@ object UtTestsDialogProcessor {
             return null
         }
 
+        if (testModule.suitableTestSourceRoots().isEmpty()) {
+            val errorMessage = """
+                No test source roots found in the project.
+                Please, create or configure at least one test source root.
+            """.trimIndent()
+            showErrorDialogLater(project, errorMessage, "Test source roots not found")
+            return null
+        }
+
         return GenerateTestsDialogWindow(
             GenerateTestsModel(
                 project,