Use ANSI color code to represent difference line.

Author: bjacotg

googletest/Cargo.toml

@@ -35,6 +35,7 @@ googletest_macro = { path = "../googletest_macro", version = "0.8.0" }
 anyhow = { version = "1", optional = true }
 num-traits = "0.2.15"
 regex = "1.6.0"
+anstyle = "1.0.0"
 
 [dev-dependencies]
 indoc = "2"

googletest/src/matchers/display_matcher.rs

@@ -112,9 +112,9 @@ mod tests {
                 "
                     which displays as a string which isn't equal to \"123\\n345\"
                     Difference:
-                     123
-                    +234
-                    -345
+                    123
+                    [1m[31m234[0m
+                    [1m[34m345[0m
                 "
             ))))
         )

googletest/src/matchers/eq_deref_of_matcher.rs

@@ -140,12 +140,12 @@ mod tests {
             Actual: Strukt { int: 123, string: "something" },
               which isn't equal to Strukt { int: 321, string: "someone" }
             Difference:
-             Strukt {
-            +    int: 123,
-            -    int: 321,
-            +    string: "something",
-            -    string: "someone",
-             }
+            Strukt {
+            [1m[31m    int: 123,[0m
+            [1m[34m    int: 321,[0m
+            [1m[31m    string: "something",[0m
+            [1m[34m    string: "someone",[0m
+            }
             "#})))
         )
     }

googletest/src/matchers/eq_matcher.rs

@@ -12,9 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use anstyle::{Color, Style};
+
 use crate::matcher::{Matcher, MatcherResult};
 use crate::matcher_support::edit_distance;
-use std::{borrow::Cow, fmt::Debug, marker::PhantomData};
+use std::{borrow::Cow, fmt::Debug, fmt::Write, marker::PhantomData};
 
 /// Matches a value equal (in the sense of `==`) to `expected`.
 ///
@@ -178,6 +180,12 @@ pub(super) fn create_diff_reversed(
     }
 }
 
+const EXTRA_LEFT_STYLE: Style =
+    Style::new().bold().fg_color(Some(Color::Ansi(anstyle::AnsiColor::Red)));
+const EXTRA_RIGHT_STYLE: Style =
+    Style::new().bold().fg_color(Some(Color::Ansi(anstyle::AnsiColor::Blue)));
+const COMMENT_STYLE: Style = Style::new().italic();
+
 fn edit_list_summary(edit_list: &[edit_distance::Edit<&str>]) -> String {
     let mut summary = String::new();
     // Use to collect common line and compress them.
@@ -188,15 +196,15 @@ fn edit_list_summary(edit_list: &[edit_distance::Edit<&str>]) -> String {
                 common_line_buffer.push(*left);
                 continue;
             }
-            edit_distance::Edit::ExtraLeft(left) => ("+", *left),
-            edit_distance::Edit::ExtraRight(right) => ("-", *right),
-            edit_distance::Edit::AdditionalLeft => ("<---- remaining lines omitted ---->", ""),
+            edit_distance::Edit::ExtraLeft(left) => (EXTRA_LEFT_STYLE, *left),
+            edit_distance::Edit::ExtraRight(right) => (EXTRA_RIGHT_STYLE, *right),
+            edit_distance::Edit::AdditionalLeft => {
+                (COMMENT_STYLE, "<---- remaining lines omitted ---->")
+            }
         };
         summary.push_str(&compress_common_lines(std::mem::take(&mut common_line_buffer)));
 
-        summary.push('\n');
-        summary.push_str(start);
-        summary.push_str(line);
+        write!(&mut summary, "\n{}{line}{}", start.render(), start.render_reset()).unwrap();
     }
     summary.push_str(&compress_common_lines(common_line_buffer));
 
@@ -211,7 +219,6 @@ fn compress_common_lines(common_lines: Vec<&str>) -> String {
         let mut all_lines = String::new();
         for line in common_lines {
             all_lines.push('\n');
-            all_lines.push(' ');
             all_lines.push_str(line);
         }
         return all_lines;
@@ -221,18 +228,18 @@ fn compress_common_lines(common_lines: Vec<&str>) -> String {
 
     for line in &common_lines[0..COMMON_LINES_CONTEXT_SIZE] {
         truncated_lines.push('\n');
-        truncated_lines.push(' ');
         truncated_lines.push_str(line);
     }
 
     truncated_lines.push_str(&format!(
-        "\n<---- {} common lines omitted ---->",
-        common_lines.len() - 2 * COMMON_LINES_CONTEXT_SIZE
+        "\n{}<---- {} common lines omitted ---->{}",
+        COMMENT_STYLE.render(),
+        common_lines.len() - 2 * COMMON_LINES_CONTEXT_SIZE,
+        COMMENT_STYLE.render_reset(),
     ));
 
     for line in &common_lines[common_lines.len() - COMMON_LINES_CONTEXT_SIZE..common_lines.len()] {
         truncated_lines.push('\n');
-        truncated_lines.push(' ');
         truncated_lines.push_str(line);
     }
     truncated_lines
@@ -296,12 +303,12 @@ mod tests {
             Actual: Strukt { int: 123, string: "something" },
               which isn't equal to Strukt { int: 321, string: "someone" }
             Difference:
-             Strukt {
-            +    int: 123,
-            -    int: 321,
-            +    string: "something",
-            -    string: "someone",
-             }
+            Strukt {
+            [1m[31m    int: 123,[0m
+            [1m[34m    int: 321,[0m
+            [1m[31m    string: "something",[0m
+            [1m[34m    string: "someone",[0m
+            }
             "#})))
         )
     }
@@ -318,12 +325,12 @@ mod tests {
             Actual: [1, 2, 3],
               which isn't equal to [1, 3, 4]
             Difference:
-             [
-                 1,
-            +    2,
-                 3,
-            -    4,
-             ]
+            [
+                1,
+            [1m[31m    2,[0m
+                3,
+            [1m[34m    4,[0m
+            ]
             "#})))
         )
     }
@@ -340,13 +347,13 @@ mod tests {
             Actual: [1, 2, 3, 4, 5],
               which isn't equal to [1, 3, 5]
             Difference:
-             [
-                 1,
-            +    2,
-                 3,
-            +    4,
-                 5,
-             ]
+            [
+                1,
+            [1m[31m    2,[0m
+                3,
+            [1m[31m    4,[0m
+                5,
+            ]
             "#})))
         )
     }
@@ -359,17 +366,17 @@ mod tests {
             err(displays_as(contains_substring(indoc! {
             "
             Difference:
-             [
-            +    1,
-            +    2,
-                 3,
-                 4,
-            <---- 43 common lines omitted ---->
-                 48,
-                 49,
-            -    50,
-            -    51,
-             ]"})))
+            [
+            [1m[31m    1,[0m
+            [1m[31m    2,[0m
+                3,
+                4,
+            [3m<---- 43 common lines omitted ---->[0m
+                48,
+                49,
+            [1m[34m    50,[0m
+            [1m[34m    51,[0m
+            ]"})))
         )
     }
 
@@ -381,17 +388,17 @@ mod tests {
             err(displays_as(contains_substring(indoc! {
             "
             Difference:
-             [
-            +    1,
-            +    2,
-                 3,
-                 4,
-                 5,
-                 6,
-                 7,
-            -    8,
-            -    9,
-             ]"})))
+            [
+            [1m[31m    1,[0m
+            [1m[31m    2,[0m
+                3,
+                4,
+                5,
+                6,
+                7,
+            [1m[34m    8,[0m
+            [1m[34m    9,[0m
+            ]"})))
         )
     }
 
@@ -403,14 +410,14 @@ mod tests {
             err(displays_as(contains_substring(indoc! {
             "
             Difference:
-             [
-                 1,
-            <---- 46 common lines omitted ---->
-                 48,
-                 49,
-            -    50,
-            -    51,
-             ]"})))
+            [
+                1,
+            [3m<---- 46 common lines omitted ---->[0m
+                48,
+                49,
+            [1m[34m    50,[0m
+            [1m[34m    51,[0m
+            ]"})))
         )
     }
 
@@ -422,14 +429,14 @@ mod tests {
             err(displays_as(contains_substring(indoc! {
             "
             Difference:
-             [
-            +    1,
-            +    2,
-                 3,
-                 4,
-            <---- 46 common lines omitted ---->
-                 51,
-             ]"})))
+            [
+            [1m[31m    1,[0m
+            [1m[31m    2,[0m
+                3,
+                4,
+            [3m<---- 46 common lines omitted ---->[0m
+                51,
+            ]"})))
         )
     }
 
@@ -473,10 +480,10 @@ mod tests {
             result,
             err(displays_as(contains_substring(indoc!(
                 r#"
-                     First line
-                    +Second line
-                    -Second lines
-                     Third line
+                First line
+                [1m[31mSecond line[0m
+                [1m[34mSecond lines[0m
+                Third line
                 "#
             ))))
         )