diff --git a/tests/00support.tests b/tests/00support.tests
index 94ade3b17..6d11e9424 100644
--- a/tests/00support.tests
+++ b/tests/00support.tests
@@ -16,6 +16,7 @@ out-lit: sizeof( test::Wrmrmpft<test::Murpf> )   =   1
 out-lit: sizeof( test::Wrmrmpft<test::Murpf> )   =   1
 out-lit: sizeof( test::Wrmrmpft<test::Murpf> )   =   1
 out-lit: sizeof( test::Wrmrmpft<test::Murpf> )   =   1
+return: 0
 END
 
 
@@ -85,6 +86,7 @@ out: Testing invocation with cmdline: 		SingleTestID spam --group TestGroupID
 out: --> Testgroup=TestGroupID
 out: --> Test-ID  =SingleTestID
 out: --> remaining=SingleTestID spam --eggs
+return: 0
 END
 
 
diff --git a/tests/10exception.tests b/tests/10exception.tests
index 38076875e..fb151a375 100644
--- a/tests/10exception.tests
+++ b/tests/10exception.tests
@@ -17,6 +17,7 @@ out: 2nd intermediate handler caught: LUMIERA_ERROR_STATE:unforeseen state -- ca
 out: caught lumiera::Error: LUMIERA_ERROR_CONFIG:misconfiguration -- caused by: LUMIERA_ERROR_EXTERNAL:failure in external service \(test-8\)\.
 out: caught lumiera::Error: LUMIERA_ERROR_LIFE_AND_UNIVERSE:and everything\? \(what is the answer\?\)\.
 out: caught error::Logic: LUMIERA_ERROR_LOGIC:internal logic broken \(the big bang\). -- caused by: LUMIERA_ERROR_LIFE_AND_UNIVERSE:and everything\? \(what is the answer\?\)\.
+return: 0
 END
 
 
diff --git a/tests/11time.tests b/tests/11time.tests
index fbdd631a9..b7aef47d3 100644
--- a/tests/11time.tests
+++ b/tests/11time.tests
@@ -3,10 +3,13 @@ TESTING "Time conversion" ./test-time
 TEST "basic functionality" basic <<END
 err: ECHO: .*: 0:00:00.000
 err: ECHO: .*: 3:55:20.700
+return: 0
 END
 
 TEST "frame rate dependent calculations" fps <<END
+return: 0
 END
 
 TEST "ntsc drop-frame calculations" ntsc_drop_frame << END
+return: 0
 END
diff --git a/tests/12metaprogramming.tests b/tests/12metaprogramming.tests
index ea54b6dd9..8ba95bb83 100644
--- a/tests/12metaprogramming.tests
+++ b/tests/12metaprogramming.tests
@@ -172,6 +172,7 @@ END
 TEST "Lumiera Iterator Concept" IterAdapter_test 20 <<END
 out: ::20::19::18::17::16::15::14::13::12::11::10::9::8::7::6::5::4::3::2::1
 out: ::0::1::2::3::4::5::6::7::8::9::10::11::12::13::14::15::16::17::18::19
+return: 0
 END
 
 
@@ -208,6 +209,7 @@ out: iter::eachValForKey::.+::.+::.+::.+::.+::.+::.+::.+::.+::.+
 out-lit: snapshot-0-1-2-3-4-5-6-7-8-9
 out-lit: snapshot-0-1-2-3-4-5-6-7-8-9
 out-lit: snapshot-22-44
+return: 0
 END
 
 
@@ -224,6 +226,7 @@ out-lit: ::13::17::19::23::25::29::31::35::37::41::43::47::49::53::55::59
 out-lit: ::20::19::18::17::16::15::14::13::12::11::10::9::8::7::6::5::4::3::2::1
 out-lit: ::-20::-19::-18::-17::-16::-15::-14::-13::-12::-11::-10::-9::-8::-7::-6::-5::-4::-3::-2::-1
 out-lit: ::22::21::20::19::18::17::16::15::14::13::12::11::10::9::8::7::6::5::4::3
+return: 0
 END
 
 
@@ -244,6 +247,7 @@ out: distinct_keys::0::1::2::3::4::5::6::7::8::9::10::11::12
 out: values_4_key(::[0-9]{1,2})+
 out: distinct_keys(::[0-9]{1,2}){13}
 out: values_4_key(::[0-9]{1,2})+
+return: 0
 END
 
 
@@ -252,6 +256,7 @@ out-lit: 1-2-3-4-5-6-7-8
 out-lit: 0-1-2-3-4-0-1-2-3-4-5-6-0-1-2-3-4-5-6-7-8
 out-lit: 0-1-2-3-4-5-6-7-8
 out-lit: 0-1-2-3-4-5-6-7-8
+return: 0
 END
 
 
@@ -286,6 +291,7 @@ out: can_IterForEach<ForwardRangeIter>	 : Yes
 out: can_IterForEach<TransformedForwardIter>	 : Yes
 out: can_IterForEach<FilteredForwardIter>	 : Yes
 out: can_IterForEach<CustomForwardIter>	 : Yes
+return: 0
 END
 
 
@@ -323,16 +329,19 @@ out-lit:  :.
 out-lit: --baseclass--
 out: .+#1.+ Type: Impl  REF  Address. 0x.+
 out-lit:  :.
+return: 0
 END
 
 
 TEST "Helper to show demangled C++ names" TypeDemangling_test <<END
 out: .+lib.meta.test.Space.+Outer.+Inner
 out-lit: lib::meta::test::Space const* (*)(lib::meta::test::Outer<lib::meta::test::Space>::Inner const&&)
+return: 0
 END
 
 
 TEST "Helper for human readable type display" TypeDisplay_test <<END
+return: 0
 END
 
 
@@ -683,6 +692,7 @@ out: :0:1$
 out: :0:1:2:3:4:5
 out: :0$
 out: :0:1$
+return: 0
 END
 
 
diff --git a/tests/15library.tests b/tests/15library.tests
index 4f9441cea..f19fddee8 100644
--- a/tests/15library.tests
+++ b/tests/15library.tests
@@ -83,6 +83,7 @@ out: Access.F\* as B&.            .+B.. adr=╲\w{8} ↗«B»
 out: Access.F\* as E&*.           .+E.. adr=╲\w{8} ↗«F»
 out-lit: Access(int as double) --->2
 out-lit: Access(float as long) --->3
+return: 0
 END
 
 
@@ -118,6 +119,7 @@ out-lit: 2|oΩo|
 out-lit: 3|Ωoo|
 out-lit: -->Ω ooΩ oΩo Ωoo
 out-lit: Standard Cmdlineformat:one  two
+return: 0
 END
 
 
@@ -194,10 +196,12 @@ out: ID<Fork>-Fork.0..
 out: ID<Fork>-special
 out: sizeof\( idi::EntryID<Fork> \) .+ =
 out: sizeof\( idi::BareEntryID \)   .+ =
+return: 0
 END
 
 
 TEST "formatting/string conversion in output" FormatCOUT_test <<END
+return: 0
 END
 
 
@@ -361,6 +365,7 @@ END
 
 TEST "inline val/ref wrapper" ItemWrapper_test <<END
 out: ItemWrapper: sizeof\( wrapper::ItemWrapper<.+ =   .
+return: 0
 END
 
 
@@ -385,6 +390,7 @@ out-lit: removed 0 1 2 3 4 5 6 7 8 9 ---> [  ]
 out-lit: removed 0 1 2 3 4 5 6 7 8   ---> [ 9 ]
 out-lit: removed   1 2 3 4 5 6 7 8 9 ---> [ 0 ]
 out-lit: removed 0 1 2 3 4   6 7 8 9 ---> [ 5 ]
+return: 0
 END
 
 
@@ -400,12 +406,14 @@ out-lit: '§&Ω%€  leading garbage' --> 'leading_garbage'
 out-lit: 'mixed    Ω   garbage' --> 'mixed_garbage'
 out-lit: 'Bääääh!!' --> 'Bh'
 out-lit: '§&Ω%€' --> ''
+return: 0
 END
 
 
 TEST "ScopedHolder_test" ScopedHolder_test <<END
 out: checking ScopedHolder<Dummy>...
 out: checking ScopedPtrHolder<Dummy>...
+return: 0
 END
 
 
@@ -424,6 +432,7 @@ out-lit: .
 out-lit: ..*** resize table to 16 elements
 out-lit: .
 out-lit: .throw some exceptions...
+return: 0
 END
 
 
@@ -449,6 +458,7 @@ out: ➢➢.d.
 out-lit: ➢➢ e f
 out-lit: ➢➢/usr/bin
 out-lit: ➢➢/usr/lib
+return: 0
 END
 
 
@@ -458,6 +468,7 @@ out-lit: ctor TargetObj(23) successful
 out-lit: calling a non-static method on the Singleton instance
 out-lit: .....TargetObj(23): data="***********************", array[23]={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,}
 out-lit: dtor ~TargetObj(23) successful
+return: 0
 END
 
 
@@ -467,6 +478,7 @@ out-lit: ctor TargetObj(13) successful
 out-lit: calling a non-static method on the Singleton-Implementation
 out-lit: .....TargetObj(13): data="*************", array[13]={0,1,2,3,4,5,6,7,8,9,10,11,12,}
 out-lit: dtor ~TargetObj(13) successful
+return: 0
 END
 
 
@@ -480,6 +492,7 @@ out-lit: Mock_1::doIt() call=4
 out-lit: Mock_1::doIt() call=5
 out-lit: Mock_2::doIt() call=1
 out-lit: TestSingletonO::doIt() call=3
+return: 0
 END
 
 
diff --git a/tests/25fundamental.tests b/tests/25fundamental.tests
index f6fe84247..2087f2fb0 100644
--- a/tests/25fundamental.tests
+++ b/tests/25fundamental.tests
@@ -162,6 +162,7 @@ END
 
 
 TEST "Parsing time values" TimeParsing_test  <<END
+return: 0
 END
 
 
diff --git a/tests/42query.tests b/tests/42query.tests
index 6acbb7e9f..46b82366f 100644
--- a/tests/42query.tests
+++ b/tests/42query.tests
@@ -9,6 +9,7 @@ END
 TEST "normalise ID" QueryUtils_test  normaliseID  <<END
 out-lit: ..original : a A AA dufte 1a _1 A_A BÄH    White 	 space  §&Ω%€GΩ%€ar  ☠☠☠  baäääääge!!!!!  :
 out-lit: normalised : a a aA dufte o1a o_1 a_A bH o white_space gar_bage :
+return: 0
 END
 
 
diff --git a/tests/43session.tests b/tests/43session.tests
index 58e007572..9713a2cc3 100644
--- a/tests/43session.tests
+++ b/tests/43session.tests
@@ -29,10 +29,12 @@ TEST "verify MObject interface" MObjectInterface_test <<END
 out: Clip\.[0-9]{3}
 out: Label\.[0-9]{3}
 out: DummyMO\.[0-9]{3}
+return: 0
 END
 
 
 TEST "SessionElementTracker_test" SessionElementTracker_test <<END
+return: 0
 END
 
 
@@ -79,7 +81,7 @@ out: Asset\(VIDEO:lumi.test-2 v1\)
 out: Placement<Clip> .................................. use-cnt=4 ID.\w{16}
 out: Placement<Clip> .................................. use-cnt=5 ID.\w{16}
 out: \(VIDEO:lumi.test-1 v1\)
-
+return: 0
 END
 
 
@@ -103,12 +105,14 @@ out: Placement<test::TestSubMO21> ..................... use-cnt=2 ID.\w{16}
 out: Placement<Clip> .................................. use-cnt=2 ID.\w{16}
 out: specialAPI()
 out: pID\(\w{6,16}\)
+return: 0
 END
 
 
 TEST "PlacementRef_test" PlacementRef_test <<END
 out: Placement<test::TestSubMO21> ..................... use-cnt=2 ID.\w{16}
 out: specialAPI()
+return: 0
 END
 
 
@@ -124,6 +128,7 @@ out: ^::Placement<test::TestClip> ........................ use-cnt=2
 out: ^ ::Placement<test::TestClip> ........................ use-cnt=1
 out: ^ ...1 elements at Level 1
 out: ^...3 elements at Level 0
+return: 0
 END
 
 
@@ -136,6 +141,7 @@ out: Placement<test::TestSubMO21> ..................... use-cnt=1
 out: path to root starting at Placement<test::TestSubMO1> ...................... use-cnt=1
 out: Placement<test::TestSubMO2> ...................... use-cnt=1
 out: Placement<Label> ................................. use-cnt=1
+return: 0
 END
 
 
@@ -224,6 +230,7 @@ out: ^iera
 out: ^miera
 out: ^umiera
 out: ^Lumiera
+return: 0
 END
 
 
@@ -267,6 +274,7 @@ out: now resetting this session.
 out: creating new Session 3
 out: Session-Impl\(3\)::implementationService\(\)
 out: current Session-Impl-ID = 3
+return: 0
 END
 
 
diff --git a/tests/44builder.tests b/tests/44builder.tests
index 89a6d6ff6..cdb38cbf8 100644
--- a/tests/44builder.tests
+++ b/tests/44builder.tests
@@ -8,6 +8,7 @@ out: apply \(tool, test1\);
 out: treat \(AbstractMO&\);
 out: apply \(tool, test2\);
 out: catch-all-function called...
+return: 0
 END
 
 
diff --git a/tests/45controller.tests b/tests/45controller.tests
index e235cf1a9..c79ef6d99 100644
--- a/tests/45controller.tests
+++ b/tests/45controller.tests
@@ -4,6 +4,7 @@ TESTING "Component Test Suite: Proc-Layer controller" ./test-suite --group=contr
 
 
 TEST "CommandBasic_test" CommandBasic_test <<END
+return: 0
 END
 
 
@@ -32,6 +33,7 @@ out: modified: Command-State. arguments=Closure\(123ms,unbelievable,..\), <mem:
 out: copied  : Command-State. arguments=Closure\(.+s.*,Lumiera rocks,..\), <mem: START...Lumiera rocks>.
 out: undo... memento=START...doIt\( Time=.+s.* "Lumiera rocks" rand=.. \)undoIt\(time=.+s\)----memento-:START...Lumiera rocksLumiera rocks
 out: RESET...undoIt\(time=.+s\)----memento-:START...doIt\( Time=.+s.* "Lumiera rocks" rand=.. \)undoIt\(time=.+s\)----memento-:START...Lumiera rocksLumiera rocks
+return: 0
 END
 
 
@@ -47,6 +49,7 @@ TEST "Command functor and UNDO functor" CommandMutation_test <<END
 out: empty placeholder closure: Closure\(0\)
 out: param values: Closure\(23\)
 out: saved state: 11
+return: 0
 END
 
 
diff --git a/tests/46engine.tests b/tests/46engine.tests
index fad64e4a5..968639754 100644
--- a/tests/46engine.tests
+++ b/tests/46engine.tests
@@ -23,6 +23,7 @@ END
 
 
 TEST "buffer metadata and state transitions" BufferMetadata_test <<END
+return: 0
 END
 
 
diff --git a/tests/48proc-operate.tests b/tests/48proc-operate.tests
index ab07012a1..afa182280 100644
--- a/tests/48proc-operate.tests
+++ b/tests/48proc-operate.tests
@@ -9,8 +9,10 @@ out-lit: accessing "test-2" (dur=≺25s≻)...
 out-lit:  Channel-0: nameID=video codecID=H264
 out-lit:  Channel-1: nameID=audio-L codecID=PCM
 out-lit:  Channel-2: nameID=audio-R codecID=PCM
+return: 0
 END
 
 
 PLANNED "RenderSegment_test" RenderSegment_test <<END
+return: 0
 END
diff --git a/tests/80-regression.tests b/tests/80-regression.tests
index f21db6990..fc016e88c 100644
--- a/tests/80-regression.tests
+++ b/tests/80-regression.tests
@@ -4,8 +4,10 @@ TESTING "Regression Tests: Known bugs" ./test-suite --group=regressiongui
 
 TEST "Smile test" HelloBug_test <<END
 err: hello sunshine
+return: 0
 END
 
 
 PLANNED "Suicide test" ElectricSuicide_test <<END
+return: 42
 END