doctests = """ ########### Tests mostly copied from test_listcomps.py ############ Test simple loop with conditional >>> sum({i*i for i in range(100) if i&1 == 1}) 166650 Test simple case >>> {2*y + x + 1 for x in (0,) for y in (1,)} {3} Test simple nesting >>> list(sorted({(i,j) for i in range(3) for j in range(4)})) [(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)] Test nesting with the inner expression dependent on the outer >>> list(sorted({(i,j) for i in range(4) for j in range(i)})) [(1, 0), (2, 0), (2, 1), (3, 0), (3, 1), (3, 2)] Test the idiom for temporary variable assignment in comprehensions. >>> sorted({j*j for i in range(4) for j in [i+1]}) [1, 4, 9, 16] >>> sorted({j*k for i in range(4) for j in [i+1] for k in [j+1]}) [2, 6, 12, 20] >>> sorted({j*k for i in range(4) for j, k in [(i+1, i+2)]}) [2, 6, 12, 20] Not assignment >>> sorted({i*i for i in [*range(4)]}) [0, 1, 4, 9] >>> sorted({i*i for i in (*range(4),)}) [0, 1, 4, 9] Make sure the induction variable is not exposed >>> i = 20 >>> sum({i*i for i in range(100)}) 328350 >>> i 20 Verify that syntax error's are raised for setcomps used as lvalues >>> {y for y in (1,2)} = 10 # doctest: +IGNORE_EXCEPTION_DETAIL Traceback (most recent call last): ... SyntaxError: ... >>> {y for y in (1,2)} += 10 # doctest: +IGNORE_EXCEPTION_DETAIL Traceback (most recent call last): ... SyntaxError: ... Make a nested set comprehension that acts like set(range()) >>> def srange(n): ... return {i for i in range(n)} >>> list(sorted(srange(10))) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] Same again, only as a lambda expression instead of a function definition >>> lrange = lambda n: {i for i in range(n)} >>> list(sorted(lrange(10))) [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] Generators can call other generators: >>> def grange(n): ... for x in {i for i in range(n)}: ... yield x >>> list(sorted(grange(5))) [0, 1, 2, 3, 4] Make sure that None is a valid return value >>> {None for i in range(10)} {None} ########### Tests for various scoping corner cases ############ Return lambdas that use the iteration variable as a default argument >>> items = {(lambda i=i: i) for i in range(5)} >>> {x() for x in items} == set(range(5)) True Same again, only this time as a closure variable >>> items = {(lambda: i) for i in range(5)} >>> {x() for x in items} {4} Another way to test that the iteration variable is local to the list comp >>> items = {(lambda: i) for i in range(5)} >>> i = 20 >>> {x() for x in items} {4} And confirm that a closure can jump over the list comp scope >>> items = {(lambda: y) for i in range(5)} >>> y = 2 >>> {x() for x in items} {2} We also repeat each of the above scoping tests inside a function >>> def test_func(): ... items = {(lambda i=i: i) for i in range(5)} ... return {x() for x in items} >>> test_func() == set(range(5)) True >>> def test_func(): ... items = {(lambda: i) for i in range(5)} ... return {x() for x in items} >>> test_func() {4} >>> def test_func(): ... items = {(lambda: i) for i in range(5)} ... i = 20 ... return {x() for x in items} >>> test_func() {4} >>> def test_func(): ... items = {(lambda: y) for i in range(5)} ... y = 2 ... return {x() for x in items} >>> test_func() {2} """ __test__ = {'doctests' : doctests} def test_main(verbose=None): import sys from test import support from test import test_setcomps support.run_doctest(test_setcomps, verbose) # verify reference counting if verbose and hasattr(sys, "gettotalrefcount"): import gc counts = [None] * 5 for i in range(len(counts)): support.run_doctest(test_setcomps, verbose) gc.collect() counts[i] = sys.gettotalrefcount() print(counts) if __name__ == "__main__": test_main(verbose=True)