index: add tests for the tree cache

These test that we invalidate at the right levels and that we remove the
tree cache when clearing the index.

tests/index/cache.c

+#include "clar_libgit2.h"
+#include "git2.h"
+#include "index.h"
+#include "tree-cache.h"
+
+static git_repository *g_repo;
+
+void test_index_cache__initialize(void)
+{
+	g_repo = cl_git_sandbox_init("testrepo");
+}
+
+void test_index_cache__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+	g_repo = NULL;
+}
+
+void test_index_cache__read_tree_no_children(void)
+{
+	git_index *index;
+	git_index_entry entry;
+	git_tree *tree;
+	git_oid id;
+
+	cl_git_pass(git_index_new(&index));
+	cl_assert(index->tree == NULL);
+	cl_git_pass(git_oid_fromstr(&id, "45dd856fdd4d89b884c340ba0e047752d9b085d6"));
+	cl_git_pass(git_tree_lookup(&tree, g_repo, &id));
+	cl_git_pass(git_index_read_tree(index, tree));
+	git_tree_free(tree);
+
+	cl_assert(index->tree);
+	cl_assert(git_oid_equal(&id, &index->tree->oid));
+	cl_assert_equal_i(0, index->tree->children_count);
+	cl_assert_equal_i(0, index->tree->entries); /* 0 is a placeholder here */
+
+	memset(&entry, 0x0, sizeof(git_index_entry));
+	entry.path = "new.txt";
+	entry.mode = GIT_FILEMODE_BLOB;
+	git_oid_fromstr(&entry.id, "45b983be36b73c0788dc9cbcb76cbb80fc7bb057");
+
+	cl_git_pass(git_index_add(index, &entry));
+	cl_assert_equal_i(-1, index->tree->entries);
+
+	git_index_free(index);
+}
+
+void test_index_cache__read_tree_children(void)
+{
+	git_index *index;
+	git_index_entry entry;
+	git_tree *tree;
+	const git_tree_cache *cache;
+	git_oid tree_id;
+
+	cl_git_pass(git_repository_index(&index, g_repo));
+	cl_git_pass(git_index_clear(index));
+	cl_assert(index->tree == NULL);
+
+
+	/* add a bunch of entries at different levels */
+	memset(&entry, 0x0, sizeof(git_index_entry));
+	entry.path = "top-level";
+	entry.mode = GIT_FILEMODE_BLOB;
+	git_oid_fromstr(&entry.id, "45b983be36b73c0788dc9cbcb76cbb80fc7bb057");
+	cl_git_pass(git_index_add(index, &entry));
+
+
+	entry.path = "subdir/some-file";
+	cl_git_pass(git_index_add(index, &entry));
+
+	entry.path = "subdir/even-deeper/some-file";
+	cl_git_pass(git_index_add(index, &entry));
+
+	entry.path = "subdir2/some-file";
+	cl_git_pass(git_index_add(index, &entry));
+
+	cl_git_pass(git_index_write_tree(&tree_id, index));
+	cl_git_pass(git_index_clear(index));
+	cl_assert(index->tree == NULL);
+
+	cl_git_pass(git_tree_lookup(&tree, g_repo, &tree_id));
+	cl_git_pass(git_index_read_tree(index, tree));
+	git_tree_free(tree);
+
+	cl_assert(index->tree);
+	cl_assert_equal_i(2, index->tree->children_count);
+
+	/* override with a slightly different id, also dummy */
+	entry.path = "subdir/some-file";
+	git_oid_fromstr(&entry.id, "45b983be36b73c0788dc9cbcb76cbb80fc7bb058");
+	cl_git_pass(git_index_add(index, &entry));
+
+	cl_assert_equal_i(-1, index->tree->entries);
+
+	cache = git_tree_cache_get(index->tree, "subdir");
+	cl_assert(cache);
+	cl_assert_equal_i(-1, cache->entries);
+
+	cache = git_tree_cache_get(index->tree, "subdir/even-deeper");
+	cl_assert(cache);
+	cl_assert_equal_i(0, cache->entries);
+
+	cache = git_tree_cache_get(index->tree, "subdir2");
+	cl_assert(cache);
+	cl_assert_equal_i(0, cache->entries);
+
+	git_index_free(index);
+}