TestComponent: implement word-diff

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

Cargo.toml

@@ -19,3 +19,4 @@ xmpp-parsers = { version = "^0.19", features = ["component"] }
 
 [dev-dependencies]
 syntect = "5.0"
+diff = "0.1"

src/component/test.rs

@@ -25,6 +25,7 @@ use std::task::Context;
 use std::thread;
 
 use async_trait::async_trait;
+use diff;
 use futures::{task::Poll, Stream};
 use log::debug;
 use syntect::{
@@ -203,6 +204,92 @@ impl Component {
 		buf
 	}
 
+	fn hl_bg(color: String) -> String {
+		format!("{}{}", color, "\x1b[48;5;8m")
+	}
+
+	fn compare_hl(expected: &str, actual: &str) -> String {
+		let hl_expected = Component::hl(expected.clone());
+		let hl_actual = Component::hl(actual.clone());
+
+		if expected == actual {
+			return format!(
+				"\nexpected: `{}`\n  \x1b[31mactual\x1b[0m: `{}`\n",
+				hl_expected, hl_actual
+			);
+		}
+
+		let mut buf_expected = String::new();
+		let mut buf_actual = String::new();
+		let mut last_color: Option<String> = None;
+		let mut color_start = false;
+		let mut color_added = false;
+		let mut clear_bg = false;
+		for diff in diff::chars(&hl_expected, &hl_actual) {
+			match diff {
+				diff::Result::Both(l, r) => {
+					if clear_bg {
+						buf_expected.push_str("\x1b[49m");
+						buf_actual.push_str("\x1b[49m");
+						clear_bg = false;
+					}
+
+					if l == '\x1b' {
+						last_color = Some(String::from(l));
+						color_start = true;
+					} else if color_start {
+						if l == 'm' {
+							color_start = false;
+						}
+
+						last_color = last_color.clone().map(|mut c| {
+							c.push(l);
+							c
+						});
+					}
+
+					buf_expected.push(l);
+					buf_actual.push(r);
+				}
+				ref result @ diff::Result::Left(ref c)
+				| ref result @ diff::Result::Right(ref c) => {
+					clear_bg = true;
+
+					if *c == '\x1b' {
+						last_color = Some(String::from(*c));
+						color_start = true;
+						color_added = false;
+					} else if color_start {
+						last_color = last_color.clone().map(|mut color| {
+							color.push(*c);
+							color
+						});
+					}
+
+					if ! color_added && ! color_start && let Some(ref color) = last_color {
+						buf_expected.push_str(format!("{}", Component::hl_bg(color.clone())).as_str());
+						color_added = true;
+					}
+
+					if color_start && *c == 'm' {
+						color_start = false;
+					}
+
+					match result {
+						diff::Result::Left(_) => buf_expected.push(*c),
+						diff::Result::Right(_) => buf_actual.push(*c),
+						_ => unreachable!(),
+					}
+				}
+			}
+		}
+
+		format!(
+			"\nexpected: `{}`\n  \x1b[31mactual\x1b[0m: `{}`\n",
+			buf_expected, buf_actual
+		)
+	}
+
 	fn send_stanza_inner<E: Into<TestElement> + Send>(&mut self, el: E) -> Result<(), Error> {
 		let out: TestElement = el.into();
 		let dest: Jid = match out.attr("to") {
@@ -218,19 +305,9 @@ impl Component {
 					Some(expected) => match expected {
 						Expect::Element(el) => {
 							let (expected, actual) = (String::from(&el), String::from(&out));
-							let hl_expected = Component::hl(expected.clone());
-							let hl_actual = Component::hl(actual.clone());
+							debug!("{}", Component::compare_hl(&expected, &actual));
 							if expected != actual {
-								debug!(
-									"\nexpected: `{}`\n  \x1b[31mactual\x1b[0m: `{}`\n",
-									hl_expected, hl_actual
-								);
 								panic!("assertion failed: `(actual == expected)`")
-							} else {
-								debug!(
-									"\nexpected: `{}`\n  \x1b[32mactual\x1b[0m: `{}`\n",
-									hl_expected, hl_actual
-								);
 							}
 						}
 						Expect::Iq(cb, _) => match Iq::try_from(out.0.clone()) {