when running unit tests, the tester will print only failures using colorless output (this should be better for nimbuild)

tests/accept/run/tunit.nim

@@ -1,47 +0,0 @@
-import
-  unittest, macros
-
-var
-    a = 1
-    b = 22
-    c = 1
-    d = 3
-
-suite "my suite":
-  setup:
-    echo "suite setup"
-    var testVar = "from setup"
-    
-  teardown:
-    echo "suite teardown"
-
-  test "first suite test":
-    testVar = "modified"
-    echo "test var: " & testVar
-    check a > b
-
-  test "second suite test":
-    echo "test var: " & testVar
-
-proc foo: bool =
-  echo "running foo"
-  return true
-
-proc err =
-  raise newException(EArithmetic, "some exception")
-
-test "final test":
-  echo "inside suite-less test"
-
-  check:
-    a == c
-    foo()
-    d > 10
-
-test "arithmetic failure":
-  expect(EArithmetic):
-    err()
-
-  expect(EArithmetic, ESystem):
-    discard foo()
-

tests/tester.nim

@@ -391,6 +391,9 @@ proc outputJSON(reject, compile, run: TResults) =
   writeFile(jsonFile, s)
 
 proc main() =
+  os.putenv "NIMTEST_NO_COLOR", "1"
+  os.putenv "NIMTEST_OUTPUT_LVL", "PRINT_FAILURES"
+
   const
     compileJson = "compile.json"
     runJson = "run.json"