libakstdlib/tests/test_tree.c

/*
 * Depth-first tree search.
 *
 * Previously this test shared one TreeSearchParams across all three searches
 * without resetting it, so `steps` accumulated (7, then 14, then 21) and the
 * second assertion failed -- `tree` was a red test on every run. Each search
 * now gets its own params.
 *
 * Caveat worth knowing when reading the step counts below: the value is hidden
 * in tree[6], which is the last node visited in pre-, in- and post-order alike,
 * so "7 steps" holds for all three orders and does not actually distinguish
 * them -- nor does it prove that AKERR_ITERATOR_BREAK stopped anything (it does
 * not; see tests/test_tree_iterate_break.c and TODO.md 2.1.3). Visit-order
 * assertions that tell the three traversals apart are TODO.md section 1.8.
 */

#include "aksl_capture.h"

#define MAX_LEAVES     7
#define HIDDEN_VALUE   ((void *)17336)

typedef struct TreeSearchParams
{
    void *value;
    int steps;
    aksl_TreeNode *node;
} TreeSearchParams;

static akerr_ErrorContext AKERR_NOIGNORE *find_value(aksl_TreeNode *node, void *data)
{
    TreeSearchParams *parms = NULL;

    PREPARE_ERROR(e);
    FAIL_ZERO_RETURN(e, node, AKERR_NULLPOINTER, "node");
    FAIL_ZERO_RETURN(e, data, AKERR_NULLPOINTER, "data");
    parms = (TreeSearchParams *)data;
    parms->steps += 1;
    if ( node->leaf == parms->value ) {
	parms->node = node;
	FAIL_RETURN(e, AKERR_ITERATOR_BREAK, "stop");
    }
    SUCCEED_RETURN(e);
}

/*
 * Build the 3-level tree used by every case here, with the search value hidden
 * in the bottom-right leaf.
 *
 *       LEFT            RIGHT
 *               TREE[0]
 *       +--------^^---------+
 *       |                   |
 *    TREE[1]              TREE[2]
 *  +---^^---+           +---^^---+
 *  |        |           |        |
 *TREE[3] TREE[4]     TREE[5]  TREE[6]
 */
static void build_tree(aksl_TreeNode *tree, TreeSearchParams *parms)
{
    memset((void *)tree, 0x00, sizeof(aksl_TreeNode) * MAX_LEAVES);
    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];
    tree[6].leaf = HIDDEN_VALUE;

    memset((void *)parms, 0x00, sizeof(TreeSearchParams));
    parms->value = HIDDEN_VALUE;
}

static int search_finds_hidden_value(uint8_t searchmode)
{
    aksl_TreeNode tree[MAX_LEAVES];
    TreeSearchParams parms;

    build_tree(tree, &parms);

    AKSL_CHECK_OK(aksl_tree_iterate(&tree[0], &find_value, NULL, NULL,
				    searchmode, &parms, NULL));
    AKSL_CHECK(parms.node == &tree[6]);
    AKSL_CHECK(parms.steps == MAX_LEAVES);
    return 0;
}

static int test_dfs_preorder(void)
{
    return search_finds_hidden_value(AKSL_TREE_SEARCH_DFS_PREORDER);
}

static int test_dfs_inorder(void)
{
    return search_finds_hidden_value(AKSL_TREE_SEARCH_DFS_INORDER);
}

static int test_dfs_postorder(void)
{
    return search_finds_hidden_value(AKSL_TREE_SEARCH_DFS_POSTORDER);
}

/*
 * Both breadth-first modes are declared in the header but not implemented, and
 * say so through AKERR_NOT_IMPLEMENTED rather than by silently visiting nothing.
 * TODO.md 2.2.10 tracks implementing them; until then this is the contract.
 */
static int bfs_reports_not_implemented(uint8_t searchmode)
{
    aksl_TreeNode tree[MAX_LEAVES];
    TreeSearchParams parms;

    build_tree(tree, &parms);

    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&tree[0], &find_value, NULL, NULL, searchmode,
			  &parms, NULL),
	AKERR_NOT_IMPLEMENTED, "Searchmode");
    AKSL_CHECK(parms.steps == 0);
    AKSL_CHECK(parms.node == NULL);
    return 0;
}

static int test_bfs_is_not_implemented(void)
{
    return bfs_reports_not_implemented(AKSL_TREE_SEARCH_BFS);
}

static int test_bfs_right_is_not_implemented(void)
{
    return bfs_reports_not_implemented(AKSL_TREE_SEARCH_BFS_RIGHT);
}

static int test_iterate_null_arguments(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    TreeSearchParams parms;

    build_tree(tree, &parms);

    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(NULL, &find_value, NULL, NULL,
			  AKSL_TREE_SEARCH_DFS_PREORDER, &parms, NULL),
	AKERR_NULLPOINTER, "root");
    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&tree[0], NULL, NULL, NULL,
			  AKSL_TREE_SEARCH_DFS_PREORDER, &parms, NULL),
	AKERR_NULLPOINTER, "iter");
    return 0;
}

/* A callback error that is not AKERR_ITERATOR_BREAK reaches the caller. */
static int test_iterate_propagates_callback_error(void)
{
    aksl_TreeNode tree[MAX_LEAVES];
    TreeSearchParams parms;

    build_tree(tree, &parms);
    /* find_value raises AKERR_NULLPOINTER when it is handed no data. */
    AKSL_CHECK_STATUS_MSG_CONTAINS(
	aksl_tree_iterate(&tree[0], &find_value, NULL, NULL,
			  AKSL_TREE_SEARCH_DFS_PREORDER, NULL, NULL),
	AKERR_NULLPOINTER, "data");
    return 0;
}

int main(void)
{
    int failures = 0;

    akerr_init();

    AKSL_RUN(failures, test_dfs_preorder);
    AKSL_RUN(failures, test_dfs_inorder);
    AKSL_RUN(failures, test_dfs_postorder);

    AKSL_RUN(failures, test_bfs_is_not_implemented);
    AKSL_RUN(failures, test_bfs_right_is_not_implemented);
    AKSL_RUN(failures, test_iterate_null_arguments);
    AKSL_RUN(failures, test_iterate_propagates_callback_error);

    AKSL_REPORT(failures);
}