pylint/checkers/refactoring.py
def _check_simplifiable_if(self, node):
        """Check if the given if node can be simplified.

        The if statement can be reduced to a boolean expression
        in some cases. For instance, if there are two branches
        and both of them return a boolean value that depends on
        the result of the statement's test, then this can be reduced
        to `bool(test)` without losing any functionality.
        """

        if self._is_actual_elif(node):
            # Not interested in if statements with multiple branches.
            return
        if len(node.orelse) != 1 or len(node.body) != 1:
            return

        # Check if both branches can be reduced.
        first_branch = node.body[0]
        else_branch = node.orelse[0]
        if isinstance(first_branch, astroid.Return):
            if not isinstance(else_branch, astroid.Return):
                return
            first_branch_is_bool = self._is_bool_const(first_branch)
            else_branch_is_bool = self._is_bool_const(else_branch)
            reduced_to = "'return bool(test)'"
        elif isinstance(first_branch, astroid.Assign):
            if not isinstance(else_branch, astroid.Assign):
                return

            # Check if we assign to the same value
            first_branch_targets = [
                target.name
                for target in first_branch.targets
                if isinstance(target, astroid.AssignName)
            ]
            else_branch_targets = [
                target.name
                for target in else_branch.targets
                if isinstance(target, astroid.AssignName)
            ]
            if not first_branch_targets or not else_branch_targets:
                return
            if sorted(first_branch_targets) != sorted(else_branch_targets):
                return

            first_branch_is_bool = self._is_bool_const(first_branch)
            else_branch_is_bool = self._is_bool_const(else_branch)
            reduced_to = "'var = bool(test)'"
        else:
            return

        if not first_branch_is_bool or not else_branch_is_bool:
            return
        if not first_branch.value.value:
            # This is a case that can't be easily simplified and
            # if it can be simplified, it will usually result in a
            # code that's harder to understand and comprehend.
            # Let's take for instance `arg and arg <= 3`. This could theoretically be
            # reduced to `not arg or arg > 3`, but the net result is that now the
            # condition is harder to understand, because it requires understanding of
            # an extra clause:
            #   * first, there is the negation of truthness with `not arg`
            #   * the second clause is `arg > 3`, which occurs when arg has a
            #     a truth value, but it implies that `arg > 3` is equivalent
            #     with `arg and arg > 3`, which means that the user must
            #     think about this assumption when evaluating `arg > 3`.
            #     The original form is easier to grasp.
            return

        self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
def _check_simplifiable_if(self, node):
        """Check if the given if node can be simplified.

        The if statement can be reduced to a boolean expression
        in some cases. For instance, if there are two branches
        and both of them return a boolean value that depends on
        the result of the statement's test, then this can be reduced
        to `bool(test)` without losing any functionality.
        """

        if self._is_actual_elif(node):
            # Not interested in if statements with multiple branches.
            return
        if len(node.orelse) != 1 or len(node.body) != 1:
            return

        # Check if both branches can be reduced.
        first_branch = node.body[0]
        else_branch = node.orelse[0]
        if isinstance(first_branch, astroid.Return):
            if not isinstance(else_branch, astroid.Return):
                return
            first_branch_is_bool = self._is_bool_const(first_branch)
            else_branch_is_bool = self._is_bool_const(else_branch)
            reduced_to = "'return bool(test)'"
        elif isinstance(first_branch, astroid.Assign):
            if not isinstance(else_branch, astroid.Assign):
                return

            # Check if we assign to the same value
            first_branch_targets = [
                target.name
                for target in first_branch.targets
                if isinstance(target, astroid.AssignName)
            ]
            else_branch_targets = [
                target.name
                for target in else_branch.targets
                if isinstance(target, astroid.AssignName)
            ]
            if not first_branch_targets or not else_branch_targets:
                return
            if sorted(first_branch_targets) != sorted(else_branch_targets):
                return

            first_branch_is_bool = self._is_bool_const(first_branch)
            else_branch_is_bool = self._is_bool_const(else_branch)
            reduced_to = "'var = bool(test)'"
        else:
            return

        if not first_branch_is_bool or not else_branch_is_bool:
            return
        if not first_branch.value.value:
            # This is a case that can't be easily simplified and
            # if it can be simplified, it will usually result in a
            # code that's harder to understand and comprehend.
            # Let's take for instance `arg and arg <= 3`. This could theoretically be
            # reduced to `not arg or arg > 3`, but the net result is that now the
            # condition is harder to understand, because it requires understanding of
            # an extra clause:
            #   * first, there is the negation of truthness with `not arg`
            #   * the second clause is `arg > 3`, which occurs when arg has a
            #     a truth value, but it implies that `arg > 3` is equivalent
            #     with `arg and arg > 3`, which means that the user must
            #     think about this assumption when evaluating `arg > 3`.
            #     The original form is easier to grasp.
            return

        self.add_message("simplifiable-if-statement", node=node, args=(reduced_to,))
Check if the given if node can be simplified.

        The if statement can be reduced to a boolean expression
        in some cases. For instance, if there are two branches
        and both of them return a boolean value that depends on
        the result of the statement's test, then this can be reduced
        to `bool(test)` without losing any functionality.