Display modification times of input files in context and unified diff

Cargo.toml

@@ -15,6 +15,7 @@ name = "diffutils"
 path = "src/main.rs"
 
 [dependencies]
+chrono = "0.4.35"
 diff = "0.1.10"
 regex = "1.10.3"
 same-file = "1.0.6"

src/context_diff.rs

@@ -8,6 +8,7 @@ use std::io::Write;
 
 use crate::params::Params;
 use crate::utils::do_write_line;
+use crate::utils::get_modification_time;
 
 #[derive(Debug, PartialEq)]
 pub enum DiffLine {
@@ -267,10 +268,14 @@ fn make_diff(
 
 #[must_use]
 pub fn diff(expected: &[u8], actual: &[u8], params: &Params) -> Vec<u8> {
+    let from_modified_time = get_modification_time(&params.from.to_string_lossy());
+    let to_modified_time = get_modification_time(&params.to.to_string_lossy());
     let mut output = format!(
-        "*** {0}\t\n--- {1}\t\n",
+        "*** {0}\t{1}\n--- {2}\t{3}\n",
         params.from.to_string_lossy(),
-        params.to.to_string_lossy()
+        from_modified_time,
+        params.to.to_string_lossy(),
+        to_modified_time
     )
     .into_bytes();
     let diff_results = make_diff(expected, actual, params.context_count, params.brief);
@@ -717,6 +722,8 @@ mod tests {
 
     #[test]
     fn test_stop_early() {
+        use crate::assert_diff_eq;
+
         let from_filename = "foo";
         let from = ["a", "b", "c", ""].join("\n");
         let to_filename = "bar";
@@ -731,9 +738,10 @@ mod tests {
                 ..Default::default()
             },
         );
+
         let expected_full = [
-            "*** foo\t",
-            "--- bar\t",
+            "*** foo\tTIMESTAMP",
+            "--- bar\tTIMESTAMP",
             "***************",
             "*** 1,3 ****",
             "  a",
@@ -746,7 +754,7 @@ mod tests {
             "",
         ]
         .join("\n");
-        assert_eq!(diff_full, expected_full.as_bytes());
+        assert_diff_eq!(diff_full, expected_full);
 
         let diff_brief = diff(
             from.as_bytes(),
@@ -758,8 +766,9 @@ mod tests {
                 ..Default::default()
             },
         );
-        let expected_brief = ["*** foo\t", "--- bar\t", ""].join("\n");
-        assert_eq!(diff_brief, expected_brief.as_bytes());
+
+        let expected_brief = ["*** foo\tTIMESTAMP", "--- bar\tTIMESTAMP", ""].join("\n");
+        assert_diff_eq!(diff_brief, expected_brief);
 
         let nodiff_full = diff(
             from.as_bytes(),

src/lib.rs

@@ -1,5 +1,6 @@
 pub mod context_diff;
 pub mod ed_diff;
+pub mod macros;
 pub mod normal_diff;
 pub mod params;
 pub mod unified_diff;

src/macros.rs

@@ -0,0 +1,25 @@
+// asserts equality of the actual diff and expected diff
+// considering datetime varitations
+//
+// It replaces the modification time in the actual diff
+// with placeholer "TIMESTAMP" and then asserts the equality
+//
+// For eg.
+// let brief = "*** fruits_old.txt\t2024-03-24 23:43:05.189597645 +0530\n
+//              --- fruits_new.txt\t2024-03-24 23:35:08.922581904 +0530\n";
+//
+// replaced = "*** fruits_old.txt\tTIMESTAMP\n
+//             --- fruits_new.txt\tTIMESTAMP\n";
+#[macro_export]
+macro_rules! assert_diff_eq {
+    ($actual:expr, $expected:expr) => {{
+        use regex::Regex;
+        use std::str;
+
+        let diff = str::from_utf8(&$actual).unwrap();
+        let re = Regex::new(r"\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d+ [+-]\d{4}").unwrap();
+        let actual = re.replacen(diff, 2, "TIMESTAMP");
+
+        assert_eq!(actual, $expected);
+    }};
+}

src/main.rs

@@ -12,6 +12,7 @@ use std::process::{exit, ExitCode};
 
 mod context_diff;
 mod ed_diff;
+mod macros;
 mod normal_diff;
 mod params;
 mod unified_diff;