diff --git a/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestClassModel.java b/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestClassModel.java
index 0d0cf9bbe81..d3eaac25291 100644
--- a/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestClassModel.java
+++ b/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestClassModel.java
@@ -39,14 +39,19 @@ public class SimpleTestClassModel implements TestClassModel {
             return o1.getName().compareTo(o2.getName());
         }
     };
+    @NotNull
     private final File rootFile;
     private final boolean recursive;
     private final boolean excludeParentDirs;
+    @NotNull
     private final Pattern filenamePattern;
+    @NotNull
     private final String doTestMethodName;
+    @NotNull
     private final String testClassName;
-
+    @Nullable
     private Collection<TestClassModel> innerTestClasses;
+    @Nullable
     private Collection<TestMethodModel> testMethods;
 
     public SimpleTestClassModel(
diff --git a/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestMethodModel.java b/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestMethodModel.java
index b07b6ed08e1..a1927a04472 100644
--- a/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestMethodModel.java
+++ b/generators/src/org/jetbrains/jet/generators/tests/generator/SimpleTestMethodModel.java
@@ -27,12 +27,21 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 public class SimpleTestMethodModel implements TestMethodModel {
+    @NotNull
     private final File rootDir;
+    @NotNull
     private final File file;
+    @NotNull
     private final String doTestMethodName;
+    @NotNull
     private final Pattern filenamePattern;
 
-    public SimpleTestMethodModel(File rootDir, File file, String doTestMethodName, Pattern filenamePattern) {
+    public SimpleTestMethodModel(
+            @NotNull File rootDir,
+            @NotNull File file,
+            @NotNull String doTestMethodName,
+            @NotNull Pattern filenamePattern
+    ) {
         this.rootDir = rootDir;
         this.file = file;
         this.doTestMethodName = doTestMethodName;
@@ -58,6 +67,7 @@ public class SimpleTestMethodModel implements TestMethodModel {
         assert found : file.getName() + " isn't matched by regex " + filenamePattern.pattern();
         assert matcher.groupCount() == 1 : filenamePattern.pattern();
         String extractedName = matcher.group(1);
+        assert extractedName != null : "extractedName should not be null: "  + filenamePattern.pattern();
 
         String unescapedName;
         if (rootDir.equals(file.getParentFile())) {
diff --git a/generators/src/org/jetbrains/jet/generators/tests/generator/SingleClassTestModel.java b/generators/src/org/jetbrains/jet/generators/tests/generator/SingleClassTestModel.java
index be2319b6946..5b2c1947a99 100644
--- a/generators/src/org/jetbrains/jet/generators/tests/generator/SingleClassTestModel.java
+++ b/generators/src/org/jetbrains/jet/generators/tests/generator/SingleClassTestModel.java
@@ -34,11 +34,15 @@ import java.util.List;
 import java.util.regex.Pattern;
 
 public class SingleClassTestModel implements TestClassModel {
+    @NotNull
     private final File rootFile;
+    @NotNull
     private final Pattern filenamePattern;
+    @NotNull
     private final String doTestMethodName;
+    @NotNull
     private final String testClassName;
-
+    @Nullable
     private Collection<TestMethodModel> testMethods;
 
     public SingleClassTestModel(
@@ -91,6 +95,7 @@ public class SingleClassTestModel implements TestClassModel {
         return testMethods;
     }
 
+    @NotNull
     protected Collection<TestMethodModel> getTestMethodsFromFile(File file) {
         return Collections.<TestMethodModel>singletonList(new SimpleTestMethodModel(rootFile, file, doTestMethodName, filenamePattern));
     }