feat: Mock SystemTime::now() for the tests

Add a new crate `deltachat_time` with a fake `struct SystemTimeTools` for mocking
`SystemTime::now()` for test purposes. One still needs to use `std::time::SystemTime` as a struct
representing a system time. I think such a minimalistic approach is ok -- even if somebody uses the
original `SystemTime::now()` instead of the mock by mistake, that could break only tests but not the
program itself. The worst thing that can happen is that tests using `SystemTime::shift()` and
checking messages timestamps f.e. wouldn't catch the corresponding bugs, but now we don't have such
tests at all which is much worse.

Author: iequidoo

Cargo.lock

@@ -35,6 +35,7 @@ imap-proto = { git = "https://github.com/djc/tokio-imap.git", rev = "01ff256a7e4
 
 [dependencies]
 deltachat_derive = { path = "./deltachat_derive" }
+deltachat-time = { path = "./deltachat-time" }
 format-flowed = { path = "./format-flowed" }
 ratelimit = { path = "./deltachat-ratelimit" }
 
@@ -123,6 +124,7 @@ members = [
   "deltachat-rpc-server",
   "deltachat-ratelimit",
   "deltachat-repl",
+  "deltachat-time",
   "format-flowed",
 ]
 

Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "deltachat-time"
+version = "1.0.0"
+description = "Time-related tools"
+edition = "2021"
+license = "MPL-2.0"
+
+[dependencies]

deltachat-time/Cargo.toml

@@ -0,0 +1,35 @@
+#![allow(missing_docs)]
+
+use std::sync::RwLock;
+use std::time::{Duration, SystemTime};
+
+static SYSTEM_TIME_SHIFT: RwLock<Duration> = RwLock::new(Duration::new(0, 0));
+
+/// Fake struct for mocking `SystemTime::now()` for test purposes. You still need to use
+/// `SystemTime` as a struct representing a system time.
+pub struct SystemTimeTools();
+
+impl SystemTimeTools {
+    pub const UNIX_EPOCH: SystemTime = SystemTime::UNIX_EPOCH;
+
+    pub fn now() -> SystemTime {
+        return SystemTime::now() + *SYSTEM_TIME_SHIFT.read().unwrap();
+    }
+
+    /// Simulates a system clock forward adjustment by `duration`.
+    pub fn shift(duration: Duration) {
+        *SYSTEM_TIME_SHIFT.write().unwrap() += duration;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn it_works() {
+        SystemTimeTools::shift(Duration::from_secs(60));
+        let t = SystemTimeTools::now();
+        assert!(t > SystemTime::now());
+    }
+}

deltachat-time/src/lib.rs

@@ -6,7 +6,7 @@ use std::convert::{TryFrom, TryInto};
 use std::fmt;
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
-use std::time::{Duration, SystemTime};
+use std::time::Duration;
 
 use anyhow::{anyhow, bail, ensure, Context as _, Result};
 use deltachat_derive::{FromSql, ToSql};
@@ -44,7 +44,7 @@ use crate::sync::{self, Sync::*, SyncData};
 use crate::tools::{
     buf_compress, create_id, create_outgoing_rfc724_mid, create_smeared_timestamp,
     create_smeared_timestamps, get_abs_path, gm2local_offset, improve_single_line_input,
-    smeared_time, strip_rtlo_characters, time, IsNoneOrEmpty,
+    smeared_time, strip_rtlo_characters, time, IsNoneOrEmpty, SystemTime,
 };
 use crate::webxdc::WEBXDC_SUFFIX;
 
@@ -3654,7 +3654,7 @@ pub enum MuteDuration {
     Forever,
 
     /// Chat is muted for a limited period of time.
-    Until(SystemTime),
+    Until(std::time::SystemTime),
 }
 
 impl rusqlite::types::ToSql for MuteDuration {

src/chat.rs

@@ -6,7 +6,7 @@ use std::convert::{TryFrom, TryInto};
 use std::fmt;
 use std::ops::Deref;
 use std::path::{Path, PathBuf};
-use std::time::{SystemTime, UNIX_EPOCH};
+use std::time::UNIX_EPOCH;
 
 use anyhow::{bail, ensure, Context as _, Result};
 use async_channel::{self as channel, Receiver, Sender};
@@ -36,7 +36,7 @@ use crate::sql::{self, params_iter};
 use crate::sync::{self, Sync::*};
 use crate::tools::{
     duration_to_str, get_abs_path, improve_single_line_input, strip_rtlo_characters, time,
-    EmailAddress,
+    EmailAddress, SystemTime,
 };
 use crate::{chat, stock_str};
 

src/contact.rs

@@ -1051,7 +1051,7 @@ pub fn get_version_str() -> &'static str {
 
 #[cfg(test)]
 mod tests {
-    use std::time::{Duration, SystemTime};
+    use std::time::Duration;
 
     use anyhow::Context as _;
     use strum::IntoEnumIterator;
@@ -1067,7 +1067,7 @@ mod tests {
     use crate::message::{Message, Viewtype};
     use crate::receive_imf::receive_imf;
     use crate::test_utils::TestContext;
-    use crate::tools::create_outgoing_rfc724_mid;
+    use crate::tools::{create_outgoing_rfc724_mid, SystemTime};
 
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn test_wrong_db() -> Result<()> {

src/context.rs

@@ -67,7 +67,7 @@ use std::collections::BTreeSet;
 use std::convert::{TryFrom, TryInto};
 use std::num::ParseIntError;
 use std::str::FromStr;
-use std::time::{Duration, SystemTime, UNIX_EPOCH};
+use std::time::{Duration, UNIX_EPOCH};
 
 use anyhow::{ensure, Result};
 use async_channel::Receiver;
@@ -85,7 +85,7 @@ use crate::message::{Message, MessageState, MsgId, Viewtype};
 use crate::mimeparser::SystemMessage;
 use crate::sql::{self, params_iter};
 use crate::stock_str;
-use crate::tools::{duration_to_str, time};
+use crate::tools::{duration_to_str, time, SystemTime};
 
 /// Ephemeral timer value.
 #[derive(Debug, PartialEq, Eq, Copy, Clone, Serialize, Deserialize)]

src/ephemeral.rs

@@ -21,7 +21,7 @@ use crate::message::{Message, MsgId, Viewtype};
 use crate::param::{Param, Params};
 use crate::peerstate::{deduplicate_peerstates, Peerstate};
 use crate::stock_str;
-use crate::tools::{delete_file, time};
+use crate::tools::{delete_file, time, SystemTime};
 
 /// Extension to [`rusqlite::ToSql`] trait
 /// which also includes [`Send`] and [`Sync`].
@@ -848,9 +848,9 @@ pub async fn remove_unused_files(context: &Context) -> Result<()> {
             Ok(mut dir_handle) => {
                 /* avoid deletion of files that are just created to build a message object */
                 let diff = std::time::Duration::from_secs(60 * 60);
-                let keep_files_newer_than = std::time::SystemTime::now()
+                let keep_files_newer_than = SystemTime::now()
                     .checked_sub(diff)
-                    .unwrap_or(std::time::SystemTime::UNIX_EPOCH);
+                    .unwrap_or(SystemTime::UNIX_EPOCH);
 
                 while let Ok(Some(entry)) = dir_handle.next_entry().await {
                     let name_f = entry.file_name();

src/sql.rs

@@ -319,7 +319,7 @@ impl Context {
 
 #[cfg(test)]
 mod tests {
-    use std::time::{Duration, SystemTime};
+    use std::time::Duration;
 
     use anyhow::bail;
 
@@ -329,6 +329,7 @@ mod tests {
     use crate::contact::{Contact, Origin};
     use crate::test_utils::TestContext;
     use crate::token::Namespace;
+    use crate::tools::SystemTime;
 
     #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn test_config_sync_msgs() -> Result<()> {