Add Rust clone of python `prepare_and_send' test

Previous version of patch, that changed type of `dc_msg_t.text' to String had
been breaking `prepare_and_send' test in Python.

This commit adds same regression test, reimplemented in Rust, since running
Rust tests is simplier and faster.

Author: Dmitry Bogatov

src/dc_chat.rs

@@ -124,6 +124,7 @@ pub fn dc_chat_load_from_db(chat: *mut Chat, chat_id: u32) -> bool {
         return false;
     }
     unsafe { dc_chat_empty(chat) };
+    dbg!("loading chat", chat_id);
 
     let context = unsafe { (*chat).context };
 
@@ -389,6 +390,7 @@ unsafe fn prepare_msg_common<'a>(
     let mut OK_TO_CONTINUE = true;
     (*msg).id = 0i32 as uint32_t;
     (*msg).context = context;
+    dbg!("prepare_msg_common");
     if (*msg).type_0 == Viewtype::Text {
         /* the caller should check if the message text is empty */
     } else if msgtype_has_file((*msg).type_0) {
@@ -461,10 +463,13 @@ unsafe fn prepare_msg_common<'a>(
         );
         OK_TO_CONTINUE = false;
     }
+    dbg!(OK_TO_CONTINUE);
     if OK_TO_CONTINUE {
+        dbg!();
         dc_unarchive_chat(context, chat_id);
         let chat = dc_chat_new(context);
         if dc_chat_load_from_db(chat, chat_id) {
+            dbg!("chat loaded");
             if (*msg).state != DC_STATE_OUT_PREPARING {
                 (*msg).state = DC_STATE_OUT_PENDING
             }
@@ -712,6 +717,7 @@ unsafe fn prepare_msg_raw(
                 }
 
                 // add message to the database
+                dbg!("SQL insert");
 
                 if sql::execute(
                         context,

src/dc_msg.rs

@@ -1441,6 +1441,7 @@ pub fn dc_update_server_uid(
 mod tests {
     use super::*;
     use std::ffi::CStr;
+    use crate::test_utils as test;
 
     #[test]
     fn test_dc_msg_guess_msgtype_from_suffix() {
@@ -1560,4 +1561,33 @@ mod tests {
             free(mime_0 as *mut libc::c_void);
         }
     }
+
+    #[test]
+    pub fn test_prepare_message_and_send() {
+        use crate::config::Config;
+
+        unsafe {
+            let d = test::dummy_context();
+            let ctx = &d.ctx;
+            dbg!(&d.dir);
+
+            let contact = dc_create_contact(ctx, b"\x00".as_ptr().cast(), b"dest@example.com\x00".as_ptr().cast());
+            assert!(contact != 0);
+
+            let res = ctx.set_config(Config::ConfiguredAddr, Some("self@example.com"));
+            assert!(res.is_ok());
+
+            let chat = dc_create_chat_by_contact_id(ctx, contact);
+            assert!(chat != 0);
+
+            let msg = dc_msg_new(ctx, Viewtype::Text);
+            assert!(!msg.is_null());
+
+            let msg_id = dc_prepare_msg(ctx, chat, msg);
+            assert!(msg_id != 0);
+
+            let msg2 = dc_get_msg(ctx, msg_id);
+            assert!(!msg2.is_null());
+        }
+    }
 }