Partially fix flaky tests (#308)

* Minor code style changes

* Disable rendering of timestamps in tests

* Update test snapshots

* Test everything with insta macros (no more `assert(_eq)?`)

- This has the benefit of creating snapshots for everything, allowing for later diffing

* Don't use `assert_debug_snapshot` for large string outputs

- This makes snapshots more human-inspectable

* Code style improvement on two tests

- `pause_by_space`
- `rearranged_by_tab`

* Minor code style improvements

91 files changed, 2680 insertions, 2278 deletions

diff --git a/Cargo.lock b/Cargo.lock
index f0388a5..eb17e8b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -155,6 +155,7 @@ dependencies = [
  "http_req",
  "insta",
  "ipnetwork",
+ "itertools",
  "log",
  "netstat2",
  "packet-builder",
diff --git a/Cargo.toml b/Cargo.toml
index bf538e4..359e248 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -53,6 +53,7 @@ insta = "1.34.0"
 pnet_base = "0.34.0"
 packet-builder = { version = "0.7.0", git = "https://github.com/cyqsimon/packet_builder.git", branch = "patch-update" }
 rstest = "0.18.2"
+itertools = "0.11.0"
 
 [target.'cfg(target_os="windows")'.build-dependencies]
 anyhow = "1.0.75"
diff --git a/src/display/components/header_details.rs b/src/display/components/header_details.rs
index 2c32a18..e997406 100644
--- a/src/display/components/header_details.rs
+++ b/src/display/components/header_details.rs
@@ -8,17 +8,10 @@ use ratatui::{
     text::Span,
     widgets::Paragraph,
 };
+use unicode_width::UnicodeWidthStr;
 
 use crate::display::{DisplayBandwidth, UIState};
 
-const SECONDS_IN_DAY: u64 = 86400;
-
-pub struct HeaderDetails<'a> {
-    pub state: &'a UIState,
-    pub elapsed_time: std::time::Duration,
-    pub paused: bool,
-}
-
 pub fn elapsed_time(last_start_time: Instant, cumulative_time: Duration, paused: bool) -> Duration {
     if paused {
         cumulative_time
@@ -27,27 +20,46 @@ pub fn elapsed_time(last_start_time: Instant, cumulative_time: Duration, paused:
     }
 }
 
+fn format_duration(d: Duration) -> String {
+    let s = d.as_secs();
+    let days = match s / 86400 {
+        0 => "".to_string(),
+        1 => "1 day, ".to_string(),
+        n => format!("{n} days, "),
+    };
+    format!(
+        "{days}{:02}:{:02}:{:02}",
+        (s / 3600) % 24,
+        (s / 60) % 60,
+        s % 60,
+    )
+}
+
+pub struct HeaderDetails<'a> {
+    pub state: &'a UIState,
+    pub elapsed_time: Duration,
+    pub paused: bool,
+}
+
 impl<'a> HeaderDetails<'a> {
-    #[allow(clippy::int_plus_one)]
     pub fn render(&self, frame: &mut Frame<impl Backend>, rect: Rect) {
         let bandwidth = self.bandwidth_string();
-        let mut elapsed_time = None;
-        let print_elapsed_time = if self.state.cumulative_mode {
-            elapsed_time = Some(self.elapsed_time_string());
-            bandwidth.len() + elapsed_time.as_ref().unwrap().len() + 1 <= rect.width as usize
-        } else {
-            false
-        };
-
         let color = if self.paused {
             Color::Yellow
         } else {
             Color::Green
         };
 
-        if print_elapsed_time {
-            self.render_elapsed_time(frame, rect, elapsed_time.as_ref().unwrap(), color);
+        // do not render time in tests, otherwise the output becomes non-deterministic
+        // see: https://github.com/imsnif/bandwhich/issues/303
+        if cfg!(not(test)) && self.state.cumulative_mode {
+            let elapsed_time = format_duration(self.elapsed_time);
+            // only render if there is enough width
+            if bandwidth.width() + 1 + elapsed_time.width() <= rect.width as usize {
+                self.render_elapsed_time(frame, rect, &elapsed_time, color);
+            }
         }
+
         self.render_bandwidth(frame, rect, &bandwidth, color);
     }
 
@@ -97,22 +109,4 @@ impl<'a> HeaderDetails<'a> {
         let paragraph = Paragraph::new(elapsed_time_text).alignment(Alignment::Right);
         frame.render_widget(paragraph, rect);
     }
-
-    fn days_string(&self) -> String {
-        match self.elapsed_time.as_secs() / SECONDS_IN_DAY {
-            0 => "".to_string(),
-            1 => "1 day, ".to_string(),
-            n => format!("{n} days, "),
-        }
-    }
-
-    fn elapsed_time_string(&self) -> String {
-        format!(
-            "{}{:02}:{:02}:{:02} ",
-            self.days_string(),
-            (self.elapsed_time.as_secs() % SECONDS_IN_DAY) / 3600,
-            (self.elapsed_time.as_secs() % 3600) / 60,
-            self.elapsed_time.as_secs() % 60
-        )
-    }
 }
diff --git a/src/display/ui.rs b/src/display/ui.rs
index 3241b0b..00532e2 100644
--- a/src/display/ui.rs
+++ b/src/display/ui.rs
@@ -123,24 +123,17 @@ where
     }
 
     pub fn draw(&mut self, paused: bool, show_dns: bool, elapsed_time: Duration, ui_offset: usize) {
-        let state = &self.state;
-        let children = self.get_tables_to_display();
+        let layout = Layout {
+            header: HeaderDetails {
+                state: &self.state,
+                elapsed_time,
+                paused,
+            },
+            children: self.get_tables_to_display(),
+            footer: HelpText { paused, show_dns },
+        };
         self.terminal
-            .draw(|frame| {
-                let size = frame.size();
-                let total_bandwidth = HeaderDetails {
-                    state,
-                    elapsed_time,
-                    paused,
-                };
-                let help_text = HelpText { paused, show_dns };
-                let layout = Layout {
-