diff --git a/tests/basics/bool1.py b/tests/basics/bool1.py
index 99bd837927179512bf2d087166180cddc8d6924a..35d9ed8ccc0284e104177b533113b644bbf4483e 100644
--- a/tests/basics/bool1.py
+++ b/tests/basics/bool1.py
@@ -9,3 +9,9 @@ print(False or True)
 # unary operators
 print(+True)
 print(-True)
+
+# unsupported unary op
+try:
+    len(False)
+except TypeError:
+    print('TypeError')
diff --git a/tests/basics/bytearray1.py b/tests/basics/bytearray1.py
index 76e7e59753ca8d64a7f29194a0c8e069368c934d..2e47f17bf956d0fc4d76215503ded11c51180327 100644
--- a/tests/basics/bytearray1.py
+++ b/tests/basics/bytearray1.py
@@ -27,4 +27,7 @@ print(bytearray([1]) == b"1")
 print(b"1" == bytearray([1]))
 print(bytearray() == bytearray())
 
+# comparison with other type should return False
+print(bytearray() == 1)
+
 # TODO: other comparisons
diff --git a/tests/basics/bytearray_add.py b/tests/basics/bytearray_add.py
index 21a386c6e7932013ed10be0d0614c3e79f392658..a7e2b573742557e9337ed773a81e18d25b09ac66 100644
--- a/tests/basics/bytearray_add.py
+++ b/tests/basics/bytearray_add.py
@@ -12,3 +12,7 @@ print(b)
 # extend
 b.extend(bytearray(4))
 print(b)
+
+# this inplace add tests the code when the buffer doesn't need to be increased
+b = bytearray()
+b += b''
diff --git a/tests/float/float_divmod_relaxed.py b/tests/float/float_divmod_relaxed.py
index 7054d2ca679aff5c0b130fe589694be2911f4599..a9450fa2c4d94cce340095bce349e16f8edcb1b8 100644
--- a/tests/float/float_divmod_relaxed.py
+++ b/tests/float/float_divmod_relaxed.py
@@ -25,3 +25,9 @@ for i in range(25):
     for j in range(25):
         y = (j - 12.5) / 6
         test(x, y)
+
+# test division by zero error
+try:
+    divmod(1.0, 0)
+except ZeroDivisionError:
+    print('ZeroDivisionError')