Fix output \r\n stripping (#2035)

Test if output ends with `\r\n` before `\n`, since the test for `\n` will
succeed if output is terminated with `\r\n`, so `\r\n` is properly stripped
from output text.

src/output.rs

@@ -17,13 +17,13 @@ pub(crate) fn output(mut command: Command) -> Result<String, OutputError> {
       }
       match str::from_utf8(&output.stdout) {
         Err(error) => Err(OutputError::Utf8(error)),
-        Ok(utf8) => Ok(
-          if utf8.ends_with('\n') {
-            &utf8[0..utf8.len() - 1]
-          } else if utf8.ends_with("\r\n") {
-            &utf8[0..utf8.len() - 2]
+        Ok(output) => Ok(
+          if output.ends_with("\r\n") {
+            &output[0..output.len() - 2]
+          } else if output.ends_with('\n') {
+            &output[0..output.len() - 1]
           } else {
-            utf8
+            output
           }
           .to_owned(),
         ),

tests/backticks.rs

@@ -0,0 +1,17 @@
+use super::*;
+
+#[test]
+fn trailing_newlines_are_stripped() {
+  Test::new()
+    .shell(false)
+    .args(["--evaluate", "foos"])
+    .justfile(
+      "
+set shell := ['python3', '-c']
+
+foos := `print('foo' * 4)`
+      ",
+    )
+    .stdout("foofoofoofoo")
+    .run();
+}

tests/lib.rs

@@ -36,6 +36,7 @@ mod allow_duplicate_recipes;
 mod assert_stdout;
 mod assert_success;
 mod attributes;
+mod backticks;
 mod byte_order_mark;
 mod changelog;
 mod choose;