libakstdlib/tests/test_tree.c

/*
 * Tree traversal -- TODO.md section 1.8, complete.
 *
 * The old version of this file counted steps, which cannot tell the three
 * depth-first orders apart because all three visit all seven nodes -- and could
 * not prove that AKERR_ITERATOR_BREAK stopped anything either, because it hid
 * its target in tree[6], the last node visited in every depth-first order. Every
 * traversal here records the node pointers it was handed, in order, and compares
 * against the expected sequence.
 *
 * The 7-node tree used throughout:
 *
 *               TREE[0]
 *       +--------^^---------+
 *       |                   |
 *    TREE[1]              TREE[2]
 *  +---^^---+           +---^^---+
 *  |        |           |        |
 * TREE[3] TREE[4]     TREE[5]  TREE[6]
 *
 *   pre-order    0 1 3 4 2 5 6
 *   in-order     3 1 4 0 5 2 6
 *   post-order   3 4 1 5 6 2 0
 *   BFS          0 1 2 3 4 5 6
 *   BFS_RIGHT    0 2 1 6 5 4 3
 */

#include "aksl_capture.h"

#define MAX_LEAVES 7
#define MAX_VISITS 32

typedef struct VisitLog
{
    int count;
    aksl_TreeNode *seen[MAX_VISITS];
    aksl_TreeNode *break_at;    /* node to raise ITERATOR_BREAK on, or NULL */
    aksl_TreeNode *fail_at;     /* node to raise AKERR_VALUE on, or NULL */
} VisitLog;

static void visitlog_init(VisitLog *log)
{
    memset((void *)log, 0x00, sizeof(VisitLog));
}

static akerr_ErrorContext AKERR_NOIGNORE *record_visit(aksl_TreeNode *node, void *data)
{
    VisitLog *log = NULL;

    PREPARE_ERROR(e);
    FAIL_ZERO_RETURN(e, node, AKERR_NULLPOINTER, "node");
    FAIL_ZERO_RETURN(e, data, AKERR_NULLPOINTER, "data");
    log = (VisitLog *)data;
    if ( log->count < MAX_VISITS ) {
	log->seen[log->count] = node;
    }
    log->count += 1;
    if ( log->fail_at == node ) {
	FAIL_RETURN(e, AKERR_VALUE, "iterator failed at node %p", (void *)node);
    }
    if ( log->break_at == node ) {
	FAIL_RETURN(e, AKERR_ITERATOR_BREAK, "stop at node %p", (void *)node);
    }
    SUCCEED_RETURN(e);
}

static void build_tree(aksl_TreeNode *tree)
{
    int i = 0;

    for ( i = 0; i < MAX_LEAVES; i++ ) {
	memset((void *)&tree[i], 0x00, sizeof(aksl_TreeNode));
    }
    tree[0].left = &tree[1];
    tree[0].right = &tree[2];
    tree[1].left = &tree[3];
    tree[1].right = &tree[4];
    tree[2].left = &tree[5];
    tree[2].right = &tree[6];
}

/* Assert that the visit log matches `expected`, which is a list of tree indices. */
static int check_order(VisitLog *log, aksl_TreeNode *tree,
		       const int *expected, int n)
{
    int i = 0;

    if ( log->count != n ) {
	fprintf(stderr, "  CHECK FAILED: visited %d nodes, expected %d\n",
		log->count, n);
	return 1;
    }
    for ( i = 0; i < n; i++ ) {
	if ( log->seen[i] != &tree[expected[i]] ) {
	    fprintf(stderr, "  CHECK FAILED: visit %d was node %ld, expected %d\n",
		    i, (long)(log->seen[i] - tree), expected[i]);
	    return 1;
	}
    }
    return 0;
}

/* ---------------------------------------------------------------------- */
/* aksl_tree_node_init                                                    */
/* ---------------------------------------------------------------------- */

static int test_node_init_zeroes_the_links(void)
{
    aksl_TreeNode node;
    int payload = 3;

    memset((void *)&node, 0xff, sizeof(node));
    AKSL_CHECK_OK(aksl_tree_node_init(&node, &payload));
    AKSL_CHECK(node.parent == NULL);
    AKSL_CHECK(node.left == NULL);
    AKSL_CHECK(node.right == NULL);
    AKSL_CHECK(node.leaf == (void *)&payload);

    AKSL_CHECK_STATUS(aksl_tree_node_init(NULL, NULL), AKERR_NULLPOINTER);
    return 0;
}

/* ---------------------------------------------------------------------- */
/* Traversal orders                                                       */
/* ---------------------------------------------------------------------- */

static int test_preorder_visits_root_left_right(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[MAX_LEAVES] = { 0, 1, 3, 4, 2, 5, 6 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_PREORDER, &log));
    AKSL_CHECK(check_order(&log, tree, expected, MAX_LEAVES) == 0);
    return 0;
}

static int test_inorder_visits_left_root_right(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[MAX_LEAVES] = { 3, 1, 4, 0, 5, 2, 6 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_INORDER, &log));
    AKSL_CHECK(check_order(&log, tree, expected, MAX_LEAVES) == 0);
    return 0;
}

static int test_postorder_visits_left_right_root(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[MAX_LEAVES] = { 3, 4, 1, 5, 6, 2, 0 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_POSTORDER, &log));
    AKSL_CHECK(check_order(&log, tree, expected, MAX_LEAVES) == 0);
    return 0;
}

/* AKSL_TREE_SEARCH_DFS is documented as an alias for the pre-order mode. */
static int test_dfs_is_an_alias_for_preorder(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[MAX_LEAVES] = { 0, 1, 3, 4, 2, 5, 6 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS, &log));
    AKSL_CHECK(check_order(&log, tree, expected, MAX_LEAVES) == 0);
    return 0;
}

/*
 * BFS was AKERR_NOT_IMPLEMENTED, and the lalloc/lfree parameters that existed to
 * serve it were defaulted and then never called -- TODO.md 2.2.8 and 2.2.10.
 * Both modes work now, and the allocator test below proves the queue is real.
 */
static int test_bfs_visits_level_by_level(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[MAX_LEAVES] = { 0, 1, 2, 3, 4, 5, 6 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_BFS, &log));
    AKSL_CHECK(check_order(&log, tree, expected, MAX_LEAVES) == 0);
    return 0;
}

static int test_bfs_right_visits_right_child_first(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[MAX_LEAVES] = { 0, 2, 1, 6, 5, 4, 3 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_BFS_RIGHT, &log));
    AKSL_CHECK(check_order(&log, tree, expected, MAX_LEAVES) == 0);
    return 0;
}

/* AKSL_TREE_SEARCH_VISIT: this node and no further. */
static int test_visit_mode_does_not_descend(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;
    static const int expected[1] = { 0 };

    build_tree(tree);
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_VISIT, &log));
    AKSL_CHECK(check_order(&log, tree, expected, 1) == 0);
    return 0;
}

/* ---------------------------------------------------------------------- */
/* Custom allocator                                                       */
/* ---------------------------------------------------------------------- */

static int counting_alloc_calls = 0;
static int counting_free_calls = 0;

static akerr_ErrorContext AKERR_NOIGNORE *counting_alloc(size_t size, void **dest)
{
    counting_alloc_calls += 1;
    return aksl_malloc(size, dest);
}

static akerr_ErrorContext AKERR_NOIGNORE *counting_free(void *ptr)
{
    counting_free_calls += 1;
    return aksl_free(ptr);
}

/*
 * TODO.md 1.8: "Custom lalloc/lfree are actually invoked -- currently they are
 * stored and never called". They are called now, once per node enqueued, and
 * every allocation is released. The depth-first modes allocate nothing at all,
 * which is the other half of the contract.
 */
static int test_custom_allocator_is_used_and_balanced(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);
    visitlog_init(&log);
    counting_alloc_calls = 0;
    counting_free_calls = 0;

    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit,
				    &counting_alloc, &counting_free,
				    AKSL_TREE_SEARCH_BFS, &log));
    AKSL_CHECK(log.count == MAX_LEAVES);
    /* One queue entry per node visited, and every one of them released. */
    AKSL_CHECK(counting_alloc_calls == MAX_LEAVES);
    AKSL_CHECK(counting_free_calls == MAX_LEAVES);

    /* Depth-first needs no queue, so it must not touch the allocator. */
    counting_alloc_calls = 0;
    counting_free_calls = 0;
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit,
				    &counting_alloc, &counting_free,
				    AKSL_TREE_SEARCH_DFS_PREORDER, &log));
    AKSL_CHECK(counting_alloc_calls == 0);
    AKSL_CHECK(counting_free_calls == 0);
    return 0;
}

/* A break part-way through a BFS still drains the queue it had already built. */
static int test_break_during_bfs_releases_the_queue(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);
    visitlog_init(&log);
    log.break_at = &tree[1];
    counting_alloc_calls = 0;
    counting_free_calls = 0;

    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit,
				    &counting_alloc, &counting_free,
				    AKSL_TREE_SEARCH_BFS, &log));
    /* 0 and 1 visited; the walk stops at 1 with 2 still sitting in the queue. */
    AKSL_CHECK(log.count == 2);
    AKSL_CHECK(counting_alloc_calls > 0);
    AKSL_CHECK(counting_alloc_calls == counting_free_calls);
    return 0;
}

/* ---------------------------------------------------------------------- */
/* Degenerate shapes                                                      */
/* ---------------------------------------------------------------------- */

static int test_single_node_tree_visits_once_in_every_order(void)
{
    aksl_TreeNode node;
    VisitLog log;
    static const uint8_t modes[] = {
	AKSL_TREE_SEARCH_DFS_PREORDER,
	AKSL_TREE_SEARCH_DFS_INORDER,
	AKSL_TREE_SEARCH_DFS_POSTORDER,
	AKSL_TREE_SEARCH_BFS,
	AKSL_TREE_SEARCH_BFS_RIGHT,
	AKSL_TREE_SEARCH_VISIT,
    };
    size_t i = 0;

    for ( i = 0; i < sizeof(modes) / sizeof(modes[0]); i++ ) {
	AKSL_CHECK_OK(aksl_tree_node_init(&node, NULL));
	visitlog_init(&log);
	AKSL_CHECK_OK(aksl_tree_iterate(&node, &record_visit, NULL, NULL,
					modes[i], &log));
	AKSL_CHECK(log.count == 1);
	AKSL_CHECK(log.seen[0] == &node);
    }
    return 0;
}

/* Left-only and right-only chains of three nodes, no branching anywhere. */
static int test_degenerate_chains(void)
{
    aksl_TreeNode chain[3];
    VisitLog log;
    static const int forward[3] = { 0, 1, 2 };
    static const int backward[3] = { 2, 1, 0 };
    int i = 0;

    /* Left-only: 0 -> 1 -> 2 */
    for ( i = 0; i < 3; i++ ) {
	AKSL_CHECK_OK(aksl_tree_node_init(&chain[i], NULL));
    }
    chain[0].left = &chain[1];
    chain[1].left = &chain[2];

    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_PREORDER, &log));
    AKSL_CHECK(check_order(&log, chain, forward, 3) == 0);

    /* In-order down a left chain arrives at the deepest node first. */
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_INORDER, &log));
    AKSL_CHECK(check_order(&log, chain, backward, 3) == 0);

    /* Right-only: the same shape, mirrored. */
    for ( i = 0; i < 3; i++ ) {
	AKSL_CHECK_OK(aksl_tree_node_init(&chain[i], NULL));
    }
    chain[0].right = &chain[1];
    chain[1].right = &chain[2];

    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_INORDER, &log));
    AKSL_CHECK(check_order(&log, chain, forward, 3) == 0);

    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_BFS, &log));
    AKSL_CHECK(check_order(&log, chain, forward, 3) == 0);
    return 0;
}

/*
 * TODO.md 1.8 / 2.2.7: a chain deeper than the recursion can take. It used to
 * overflow the stack; it is AKERR_OUTOFBOUNDS now, and the message names the
 * documented limit. Built one node past the cap so the failure is the cap itself
 * and not some incidental shortfall. `static` because AKSL_TREE_MAX_DEPTH nodes
 * on the stack of a test function is not the point of the test.
 */
static int test_tree_deeper_than_the_cap_is_out_of_bounds(void)
{
    static aksl_TreeNode chain[AKSL_TREE_MAX_DEPTH + 2];
    VisitLog log;
    int i = 0;

    for ( i = 0; i < AKSL_TREE_MAX_DEPTH + 2; i++ ) {
	AKSL_CHECK_OK(aksl_tree_node_init(&chain[i], NULL));
    }
    for ( i = 0; i < AKSL_TREE_MAX_DEPTH + 1; i++ ) {
	chain[i].left = &chain[i + 1];
    }

    visitlog_init(&log);
    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
			  AKSL_TREE_SEARCH_DFS_PREORDER, &log),
	AKERR_OUTOFBOUNDS, "AKSL_TREE_MAX_DEPTH");

    /* Exactly at the cap is fine -- a limit, not an off-by-one. */
    chain[AKSL_TREE_MAX_DEPTH - 1].left = NULL;
    visitlog_init(&log);
    AKSL_CHECK_OK(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_PREORDER, &log));
    AKSL_CHECK(log.count == AKSL_TREE_MAX_DEPTH);

    /*
     * And again leaning right. The recursion counts depth separately for each
     * child, so a chain that only ever goes left says nothing about whether the
     * right-hand descent counts at all -- mutation testing found exactly that:
     * changing the right child's `depth + 1` to `depth + 0` survived the whole
     * suite, because nothing here had ever recursed right more than three deep.
     */
    for ( i = 0; i < AKSL_TREE_MAX_DEPTH + 2; i++ ) {
	AKSL_CHECK_OK(aksl_tree_node_init(&chain[i], NULL));
    }
    for ( i = 0; i < AKSL_TREE_MAX_DEPTH + 1; i++ ) {
	chain[i].right = &chain[i + 1];
    }
    visitlog_init(&log);
    AKSL_CHECK_STATUS(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_DFS_PREORDER, &log),
		      AKERR_OUTOFBOUNDS);

    /* Both orders that descend right, so in-order and post-order count too. */
    visitlog_init(&log);
    AKSL_CHECK_STATUS(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_DFS_INORDER, &log),
		      AKERR_OUTOFBOUNDS);
    visitlog_init(&log);
    AKSL_CHECK_STATUS(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_DFS_POSTORDER, &log),
		      AKERR_OUTOFBOUNDS);

    /* And breadth-first, whose depth is carried on the queue entry instead. */
    visitlog_init(&log);
    AKSL_CHECK_STATUS(aksl_tree_iterate(&chain[0], &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_BFS, &log),
		      AKERR_OUTOFBOUNDS);
    return 0;
}

/*
 * A child pointing back at an ancestor. This used to recurse until the process
 * died. The depth-first walk carries the ancestor chain and recognises the node
 * as its own forebear; the breadth-first walk has no ancestor chain to compare
 * against, so the same tree comes back as AKERR_OUTOFBOUNDS through the depth
 * cap instead -- a different status for the same shape, which the header says
 * out loud rather than leaving to be discovered.
 */
static int test_cyclic_tree_is_caught(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);
    tree[3].left = &tree[0];    /* back to the root */

    visitlog_init(&log);
    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
			  AKSL_TREE_SEARCH_DFS_PREORDER, &log),
	AKERR_CIRCULAR_REFERENCE, "own ancestor");

    visitlog_init(&log);
    AKSL_CHECK_STATUS(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_BFS, &log),
		      AKERR_OUTOFBOUNDS);
    return 0;
}

/* ---------------------------------------------------------------------- */
/* Callback control flow                                                  */
/* ---------------------------------------------------------------------- */

/*
 * The defect that made ITERATOR_BREAK useless on a tree: the recursive frame
 * that raised the break handled it in its own PROCESS/HANDLE block and returned
 * success, so the parent frame's PASS saw nothing wrong and carried straight on
 * into the sibling subtree. All seven nodes were visited no matter where the
 * break was raised. TODO.md 2.1.3.
 *
 * One case per order, each breaking on a node that is *not* last in that order --
 * which is precisely what the old test could not do, because it hid its target
 * in tree[6], the final node in all three depth-first walks.
 */
static int test_break_aborts_the_whole_traversal(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);

    /* Pre-order 0 1 3 ... : breaking at 3 is the third visit. */
    visitlog_init(&log);
    log.break_at = &tree[3];
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_PREORDER, &log));
    AKSL_CHECK(log.count == 3);

    /* In-order 3 1 4 ... : breaking at 4 is the third visit. */
    visitlog_init(&log);
    log.break_at = &tree[4];
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_INORDER, &log));
    AKSL_CHECK(log.count == 3);

    /* Post-order 3 4 1 5 ... : breaking at 5 is the fourth visit. */
    visitlog_init(&log);
    log.break_at = &tree[5];
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_DFS_POSTORDER, &log));
    AKSL_CHECK(log.count == 4);

    /* BFS 0 1 2 3 ... : breaking at 2 is the third visit. */
    visitlog_init(&log);
    log.break_at = &tree[2];
    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
				    AKSL_TREE_SEARCH_BFS, &log));
    AKSL_CHECK(log.count == 3);
    return 0;
}

/* Any other status propagates out with its message and its own status intact. */
static int test_callback_error_propagates(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);
    visitlog_init(&log);
    log.fail_at = &tree[3];

    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
			  AKSL_TREE_SEARCH_DFS_PREORDER, &log),
	AKERR_VALUE, "iterator failed at node");
    AKSL_CHECK(log.count == 3);

    /* And out of a BFS, where the queue has to be drained on the way past. */
    visitlog_init(&log);
    log.fail_at = &tree[2];
    AKSL_CHECK_STATUS(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_BFS, &log),
		      AKERR_VALUE);
    return 0;
}

/* ---------------------------------------------------------------------- */
/* Argument validation                                                    */
/* ---------------------------------------------------------------------- */

static int test_null_arguments(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);
    visitlog_init(&log);

    AKSL_CHECK_STATUS(aksl_tree_iterate(NULL, &record_visit, NULL, NULL,
					AKSL_TREE_SEARCH_DFS_PREORDER, &log),
		      AKERR_NULLPOINTER);
    AKSL_CHECK_STATUS(aksl_tree_iterate(&tree[0], NULL, NULL, NULL,
					AKSL_TREE_SEARCH_DFS_PREORDER, &log),
		      AKERR_NULLPOINTER);
    AKSL_CHECK(log.count == 0);
    return 0;
}

/*
 * TODO.md 2.2.9: the switch had no default, so an unrecognised mode -- and
 * AKSL_TREE_SEARCH_VISIT, which the header documented but nothing implemented --
 * fell straight through to SUCCEED_RETURN having visited nothing at all. A
 * traversal that silently did not happen, reported as success.
 */
static int test_unknown_searchmode_is_a_value_error(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    VisitLog log;

    build_tree(tree);
    visitlog_init(&log);

    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL, 99, &log),
	AKERR_VALUE, "unknown searchmode");
    AKSL_CHECK(log.count == 0);

    /* 6 is one past the last defined mode, and just as unacceptable. */
    AKSL_CHECK_STATUS(aksl_tree_iterate(&tree[0], &record_visit, NULL, NULL, 6, &log),
		      AKERR_VALUE);
    AKSL_CHECK(log.count == 0);
    return 0;
}

int main(void)
{
    int failures = 0;

    akerr_init();

    AKSL_RUN(failures, test_node_init_zeroes_the_links);

    AKSL_RUN(failures, test_preorder_visits_root_left_right);
    AKSL_RUN(failures, test_inorder_visits_left_root_right);
    AKSL_RUN(failures, test_postorder_visits_left_right_root);
    AKSL_RUN(failures, test_dfs_is_an_alias_for_preorder);
    AKSL_RUN(failures, test_bfs_visits_level_by_level);
    AKSL_RUN(failures, test_bfs_right_visits_right_child_first);
    AKSL_RUN(failures, test_visit_mode_does_not_descend);

    AKSL_RUN(failures, test_custom_allocator_is_used_and_balanced);
    AKSL_RUN(failures, test_break_during_bfs_releases_the_queue);

    AKSL_RUN(failures, test_single_node_tree_visits_once_in_every_order);
    AKSL_RUN(failures, test_degenerate_chains);
    AKSL_RUN(failures, test_tree_deeper_than_the_cap_is_out_of_bounds);
    AKSL_RUN(failures, test_cyclic_tree_is_caught);

    AKSL_RUN(failures, test_break_aborts_the_whole_traversal);
    AKSL_RUN(failures, test_callback_error_propagates);

    AKSL_RUN(failures, test_null_arguments);
    AKSL_RUN(failures, test_unknown_searchmode_is_a_value_error);

    AKSL_REPORT(failures);
}