Started work on bash style history

test_prof_history.c

@@ -0,0 +1,49 @@
+#include <stdio.h>
+#include <head-unit.h>
+#include "prof_history.h"
+
+void previous_on_empty_returns_null(void)
+{
+    PHistory history = p_history_new(10);
+    char *item = p_history_previous(history);
+
+    assert_is_null(item);
+}
+
+void next_on_empty_returns_null(void)
+{
+    PHistory history = p_history_new(10);
+    char *item = p_history_next(history);
+
+    assert_is_null(item);
+}
+
+void previous_once_returns_last(void)
+{
+    PHistory history = p_history_new(10);
+    p_history_append(history, "Hello");
+
+    char *item = p_history_previous(history);
+
+    assert_string_equals("Hello", item);
+}
+
+void previous_twice_when_one_returns_first(void)
+{
+    PHistory history = p_history_new(10);
+    p_history_append(history, "Hello");
+
+    p_history_previous(history);
+    char *item = p_history_previous(history);
+
+    assert_string_equals("Hello", item);
+}
+
+void register_prof_history_tests(void)
+{
+    TEST_MODULE("prof_history tests");
+    TEST(previous_on_empty_returns_null);
+    TEST(next_on_empty_returns_null);
+    TEST(previous_once_returns_last);
+    TEST(previous_twice_when_one_returns_first);
+}