PY-19738: Do not rerun tests if we can't get list of specs to rerun

When rerun, test task should provide list of test specs to rerun. If it fails to do so, no need to rerun "something".

python/src/com/jetbrains/python/PyBundle.properties

@@ -765,6 +765,8 @@ QDOC.module.path.unknown=(Module path is unknown)
 QDOC.epydoc.python2.sdk.not.found=You need configured Python 2 SDK to render <a href='http://epydoc.sourceforge.net/'>Epydoc</a> docstrings
 QDOC.sdk.not.found=You need configured Python SDK to render docstrings
 
+runcfg.tests.cant_rerun=Can't rerun tests since test IDs can't be resolved. Try to delete run configuration, and create new one using right click.
+
 ### doctest run conf
 runcfg.doctest.display_name=Doctests
 runcfg.doctest.description=Python's doctests run configuration

python/src/com/jetbrains/python/run/PythonRunner.java

@@ -25,7 +25,10 @@ import com.intellij.execution.runners.ExecutionEnvironment;
 import com.intellij.execution.runners.RunContentBuilder;
 import com.intellij.execution.ui.RunContentDescriptor;
 import com.intellij.openapi.fileEditor.FileDocumentManager;
+import com.jetbrains.python.PyBundle;
+import com.jetbrains.python.testing.PythonTestCommandLineStateBase;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * @author yole
@@ -41,12 +44,20 @@ public class PythonRunner extends DefaultProgramRunner {
     return executorId.equals(DefaultRunExecutor.EXECUTOR_ID) && profile instanceof AbstractPythonRunConfiguration;
   }
 
+  @Nullable
   @Override
   protected RunContentDescriptor doExecute(@NotNull RunProfileState state, @NotNull ExecutionEnvironment env) throws ExecutionException {
     FileDocumentManager.getInstance().saveAllDocuments();
 
     ExecutionResult executionResult;
     RunProfile profile = env.getRunProfile();
+
+    if (state instanceof PythonTestCommandLineStateBase) {
+      if (!((PythonTestCommandLineStateBase)state).isRerunEnabled()) {
+        throw new ExecutionException(PyBundle.message("runcfg.tests.cant_rerun"));
+      }
+    }
+
     if (state instanceof PythonCommandLineState && profile instanceof CommandLinePatcher) {
       executionResult = ((PythonCommandLineState)state).execute(env.getExecutor(), (CommandLinePatcher)profile);
     }

python/src/com/jetbrains/python/testing/PythonTestCommandLineStateBase.java

@@ -171,4 +171,11 @@ public abstract class PythonTestCommandLineStateBase extends PythonCommandLineSt
   protected abstract HelperPackage getRunner();
   @NotNull
   protected abstract List<String> getTestSpecs();
+
+  /**
+   * @return is it possible to rerun tests now?
+   */
+  public boolean isRerunEnabled() {
+    return !getTestSpecs().isEmpty();
+  }
 }