[console] Add failing unit test for con_buffer

I was looking through the code for Con_BufferAddText trying to figure
out what it was doing (answer: ring buffer for both text and lines) and
got suspicious about its handling of the line objects. I decided an
automated test was in order. It turns out I was right: filling the
buffer with a single long line causes the tail line to trample the
current line, setting its pointer and length to 0 when the final
character is put in the buffer.

libs/console/Makemodule.am

@@ -1,3 +1,5 @@
+include libs/console/test/Makemodule.am
+
 lib_LTLIBRARIES += libs/console/libQFconsole.la
 plugin_LTLIBRARIES += @console_plugins@
 noinst_LTLIBRARIES += @client_static_plugins@ @server_static_plugins@

libs/console/test/Makemodule.am

@@ -0,0 +1,15 @@
+libs_console_tests = \
+	libs/console/test/test-buffer
+
+TESTS += $(libs_console_tests)
+
+check_PROGRAMS += $(libs_console_tests)
+
+test_console_libs= \
+	libs/console/libQFconsole.la \
+	libs/util/libQFutil.la
+
+libs_console_test_test_buffer_SOURCES= \
+	libs/console/test/test-buffer.c
+libs_console_test_test_buffer_LDADD=		$(test_console_libs)
+libs_console_test_test_buffer_DEPENDENCIES=$(test_console_libs)

libs/console/test/test-buffer.c

@@ -0,0 +1,111 @@
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+#include <stdio.h>
+#include <stddef.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "QF/console.h"
+
+static int
+test_1 (void)
+{
+	int         ret = 1;
+	__auto_type con = Con_CreateBuffer (1024, 25);
+	if (!con) {
+		printf ("con_buffer allocation failed\n");
+		goto fail;
+	}
+	if (!con->buffer) {
+		printf ("con_buffer buffer not set\n");
+		goto fail;
+	}
+	if (!con->lines) {
+		printf ("con_buffer lines not set\n");
+		goto fail;
+	}
+	if (con->buffer_size != 1024) {
+		printf ("con_buffer buffer_size incorrect: %zd\n", con->buffer_size);
+		goto fail;
+	}
+	if (con->max_lines != 25) {
+		printf ("con_buffer max_lines incorrect: %d\n", con->max_lines);
+		goto fail;
+	}
+	if (con->num_lines != 1) {
+		printf ("con_buffer num_lines incorrect: %d\n", con->num_lines);
+		goto fail;
+	}
+	if (con->cur_line != 0) {
+		printf ("con_buffer cur_line incorrect: %d\n", con->cur_line);
+		goto fail;
+	}
+	if (con->lines[con->cur_line].text != con->buffer) {
+		printf ("con_buffer cur_line.text incorrect: %p, %p\n",
+				con->lines[con->cur_line].text, con->buffer);
+		goto fail;
+	}
+	if (con->lines[con->cur_line].len != 0) {
+		printf ("con_buffer cur_line.line incorrect: %zd\n",
+				con->lines[con->cur_line].len);
+		goto fail;
+	}
+
+	ret = 0;
+fail:
+	Con_DestroyBuffer (con);
+	return ret;
+}
+
+static int
+test_2 (void)
+{
+	int         ret = 1;
+	char        text[2049];
+
+	for (size_t i = 0; i < sizeof (text); i++) {
+		int         x = i % 13;
+		text[i] = x + (x > 9 ? 'a' - 10 : '0');
+	}
+	text[sizeof(text) - 1] = 0;
+
+	__auto_type con = Con_CreateBuffer (1024, 25);
+	Con_BufferAddText (con, text);
+
+	if (con->num_lines != 1) {
+		printf ("con_buffer num_lines incorrect: %d\n", con->num_lines);
+		goto fail;
+	}
+	if (con->cur_line != 0) {
+		printf ("con_buffer cur_line incorrect: %d\n", con->cur_line);
+		goto fail;
+	}
+	if (con->lines[con->cur_line].text != con->buffer) {
+		printf ("con_buffer cur_line.text incorrect: %p, %p\n",
+				con->lines[con->cur_line].text, con->buffer);
+		goto fail;
+	}
+	if (con->lines[con->cur_line].len != 1024) {
+		printf ("con_buffer cur_line.line incorrect: %zd\n",
+				con->lines[con->cur_line].len);
+		goto fail;
+	}
+
+	ret = 0;
+fail:
+	if (ret) {
+		printf ("%s failed\n", __FUNCTION__);
+	}
+	Con_DestroyBuffer (con);
+	return ret;
+}
+
+int
+main (void)
+{
+	int         ret = 0;
+	ret |= test_1 ();
+	ret |= test_2 ();
+	return ret;
+}