diff --git a/monticore-grammar/src/test/java/de/monticore/symbols/library/StreamTypeTest.java b/monticore-grammar/src/test/java/de/monticore/symbols/library/StreamTypeTest.java
index 65d73badd..29ef65366 100644
--- a/monticore-grammar/src/test/java/de/monticore/symbols/library/StreamTypeTest.java
+++ b/monticore-grammar/src/test/java/de/monticore/symbols/library/StreamTypeTest.java
@@ -10,6 +10,7 @@
 import de.monticore.symbols.oosymbols._symboltable.*;
 import de.monticore.types.check.SymTypeExpression;
 import de.monticore.types.check.SymTypeOfGenerics;
+import de.monticore.types.check.SymTypeOfTuple;
 import de.se_rwth.commons.logging.Log;
 import de.se_rwth.commons.logging.LogStub;
 import org.junit.jupiter.api.Assertions;
@@ -21,6 +22,7 @@
 import java.nio.file.Path;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.Collectors;
 
 public class StreamTypeTest {
 
@@ -38,7 +40,7 @@ public void init() throws URISyntaxException {
   }
 
   @Test
-  public void resolveStreamType() {
+  public void testStreamTypeResolution() {
     Optional<TypeSymbol> streamOpt = OOSymbolsMill.globalScope()
         .resolveType("Stream");
     Assertions.assertTrue(streamOpt.isPresent());
@@ -49,68 +51,90 @@ public void resolveStreamType() {
   }
 
   @Test
-  public void resolveStaticEmpty() {
-    MethodSymbol method = resolveMethod("Stream.emptyStream");
-    Assertions.assertTrue(method.getParameterList().isEmpty());
+  public void testStaticRepeat() {
+    MethodSymbol method = resolveMethod("Stream.repeat");
+    Assertions.assertEquals(method.getParameterList().size(), 2);
     assertIsStreamWithTypeVar(method.getType());
     Assertions.assertTrue(method.isIsStatic());
     List<TypeVarSymbol> typeVars = method.getSpannedScope().getLocalTypeVarSymbols();
     Assertions.assertEquals(1, typeVars.size());
-    Assertions.assertNotEquals(typeVars.get(0).getName(), "T");
+    Assertions.assertNotEquals(typeVars.get(0).getName(), "S");
   }
 
   @Test
-  public void resolveStreamMethodAppendFirst() {
-    MethodSymbol method = resolveMethod("Stream.appendFirst");
+  public void testStaticProjection() {
+    MethodSymbol method = resolveMethod("Stream.projFst");
     Assertions.assertTrue(method.isIsStatic());
-    Assertions.assertEquals(2, method.getParameterList().size());
-    Assertions.assertTrue(method.getParameterList().get(0).getType().isTypeVariable());
-    assertIsStreamWithTypeVar(method.getParameterList().get(1).getType());
+    Assertions.assertEquals(1, method.getParameterList().size());
     assertIsStreamWithTypeVar(method.getType());
+    assertIsStreamWithTupleOfTypeVars(method.getParameterList().get(0).getType());
   }
 
   @Test
-  public void resolveStreamMethodLen() {
+  public void testStreamMethodLen() {
     MethodSymbol method = resolveMethod("Stream.len");
     Assertions.assertEquals(0, method.getParameterList().size());
-    Assertions.assertTrue(method.getEnclosingScope().getSpanningSymbol() instanceof TypeSymbol);
+    Assertions.assertInstanceOf(TypeSymbol.class, method.getEnclosingScope().getSpanningSymbol());
     Assertions.assertEquals("Stream", method.getEnclosingScope().getSpanningSymbol().getName());
     Assertions.assertEquals(BasicSymbolsMill.LONG, method.getType().getTypeInfo().getName());
   }
 
   @Test
-  public void resolveStreamFunctions() {
-    resolveCommonMemberMethods("Stream");
+  public void resolveStreamMethodsTest() {
+    resolveCommonMemberMethods("UntimedStream");
     resolveCommonMemberMethods("EventStream");
     resolveCommonMemberMethods("SyncStream");
     resolveCommonMemberMethods("ToptStream");
   }
 
+  @Test
+  public void testInterfaceMethodResolution() {
+    resolveStaticMethods("Stream");
+    // methods such as "zip", "first", "nth" are not in the interface
+    // as the signatures do not match between implementations
+    resolveMethod("Stream.len");
+    resolveMethod("Stream.hasInfiniteLen");
+    resolveMethod("Stream.take");
+    resolveMethod("Stream.dropFirst");
+    resolveMethod("Stream.dropMultiple");
+    resolveMethod("Stream.times");
+    resolveMethod("Stream.infTimes");
+    resolveMethod("Stream.map");
+    resolveMethod("Stream.filter");
+    resolveMethod("Stream.takeWhile");
+    resolveMethod("Stream.dropWhile");
+    resolveMethod("Stream.rcDups");
+    resolveMethod("Stream.values");
+    resolveMethod("Stream.scanl");
+  }
+
   protected void resolveStaticMethods(String streamType) {
-    resolveMethod(streamType + ".emptyStream");
-    resolveMethod(streamType + ".appendFirst");
-    resolveMethod(streamType + ".conc");
     resolveMethod(streamType + ".repeat");
     resolveMethod(streamType + ".iterate");
   }
 
   protected void resolveCommonMemberMethods(String streamType) {
     resolveMethod(streamType + ".len");
+    resolveMethod(streamType + ".hasInfiniteLen");
     resolveMethod(streamType + ".first");
-    resolveMethod(streamType + ".dropFirst");
     resolveMethod(streamType + ".nth");
     resolveMethod(streamType + ".take");
-    resolveMethod(streamType + ".drop");
+    resolveMethod(streamType + ".dropFirst");
+    resolveMethod(streamType + ".dropMultiple");
     resolveMethod(streamType + ".times");
+    resolveMethod(streamType + ".infTimes");
     resolveMethod(streamType + ".map");
     resolveMethod(streamType + ".filter");
     resolveMethod(streamType + ".takeWhile");
     resolveMethod(streamType + ".dropWhile");
     resolveMethod(streamType + ".rcDups");
+    resolveMethod(streamType + ".zip");
+    resolveMethod(streamType + ".values");
+    resolveMethod(streamType + "scanl");
   }
 
   @Test
-  public void resolveTimedStreamMethods() {
+  public void testTimedStreamMethodsResolution() {
     resolveMethod("EventStream.delay");
     resolveMethod("EventStream.mapSlice");
     resolveMethod("EventStream.rougherTime");
@@ -118,7 +142,7 @@ public void resolveTimedStreamMethods() {
     resolveMethod("EventStream.sync");
     resolveMethod("EventStream.topt");
     resolveMethod("EventStream.untimed");
-    resolveMethod("ToptStream.sizeEps");
+    resolveMethod("ToptStream.sizeEmptyTimeslices");
     resolveMethod("SyncStream.event");
   }
 
@@ -135,6 +159,18 @@ protected void assertIsStreamWithTypeVar(SymTypeExpression type) {
     Assertions.assertTrue(((SymTypeOfGenerics) type).getArgument(0).isTypeVariable());
   }
 
+  protected void assertIsStreamWithTupleOfTypeVars(SymTypeExpression type) {
+    Assertions.assertNotNull(type);
+    Assertions.assertTrue(type.isGenericType());
+    Assertions.assertEquals("Stream", type.getTypeInfo().getName());
+    Assertions.assertEquals(1, ((SymTypeOfGenerics) type).getArgumentList().size());
+    Assertions.assertTrue(((SymTypeOfGenerics) type).getArgument(0).isTupleType());
+    Assertions.assertEquals(2, ((SymTypeOfTuple)((SymTypeOfGenerics) type).getArgument(0)).getTypeList().size());
+    List<SymTypeExpression> tuple = ((SymTypeOfTuple)((SymTypeOfGenerics) type).getArgument(0)).getTypeList();
+    Assertions.assertTrue(tuple.get(0).isTypeVariable());
+    Assertions.assertTrue(tuple.get(1).isTypeVariable());
+  }
+
   protected MethodSymbol resolveMethod(String name) {
     Optional<MethodSymbol> emptyOpt = OOSymbolsMill.globalScope().resolveMethod(name);
     Assertions.assertTrue(emptyOpt.isPresent());