reftable: utility functions

This commit provides basic utility classes for the reftable library.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

reftable/basics_test.c

@@ -0,0 +1,98 @@
+/*
+Copyright 2020 Google LLC
+
+Use of this source code is governed by a BSD-style
+license that can be found in the LICENSE file or at
+https://developers.google.com/open-source/licenses/bsd
+*/
+
+#include "system.h"
+
+#include "basics.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+struct binsearch_args {
+	int key;
+	int *arr;
+};
+
+static int binsearch_func(size_t i, void *void_args)
+{
+	struct binsearch_args *args = void_args;
+
+	return args->key < args->arr[i];
+}
+
+static void test_binsearch(void)
+{
+	int arr[] = { 2, 4, 6, 8, 10 };
+	size_t sz = ARRAY_SIZE(arr);
+	struct binsearch_args args = {
+		.arr = arr,
+	};
+
+	int i = 0;
+	for (i = 1; i < 11; i++) {
+		int res;
+		args.key = i;
+		res = binsearch(sz, &binsearch_func, &args);
+
+		if (res < sz) {
+			EXPECT(args.key < arr[res]);
+			if (res > 0) {
+				EXPECT(args.key >= arr[res - 1]);
+			}
+		} else {
+			EXPECT(args.key == 10 || args.key == 11);
+		}
+	}
+}
+
+static void test_names_length(void)
+{
+	char *a[] = { "a", "b", NULL };
+	EXPECT(names_length(a) == 2);
+}
+
+static void test_parse_names_normal(void)
+{
+	char in[] = "a\nb\n";
+	char **out = NULL;
+	parse_names(in, strlen(in), &out);
+	EXPECT(!strcmp(out[0], "a"));
+	EXPECT(!strcmp(out[1], "b"));
+	EXPECT(!out[2]);
+	free_names(out);
+}
+
+static void test_parse_names_drop_empty(void)
+{
+	char in[] = "a\n\n";
+	char **out = NULL;
+	parse_names(in, strlen(in), &out);
+	EXPECT(!strcmp(out[0], "a"));
+	EXPECT(!out[1]);
+	free_names(out);
+}
+
+static void test_common_prefix(void)
+{
+	struct strbuf s1 = STRBUF_INIT;
+	struct strbuf s2 = STRBUF_INIT;
+	strbuf_addstr(&s1, "abcdef");
+	strbuf_addstr(&s2, "abc");
+	EXPECT(common_prefix_size(&s1, &s2) == 3);
+	strbuf_release(&s1);
+	strbuf_release(&s2);
+}
+
+int basics_test_main(int argc, const char *argv[])
+{
+	RUN_TEST(test_common_prefix);
+	RUN_TEST(test_parse_names_normal);
+	RUN_TEST(test_parse_names_drop_empty);
+	RUN_TEST(test_binsearch);
+	RUN_TEST(test_names_length);
+	return 0;
+}