coverall: a unit-test instead of ignoring error.rs

.github/workflows/rust.yaml

@@ -52,7 +52,7 @@ jobs:
       run: |
         mkdir coverage
         ./grcov ./target/debug/ -s . -t lcov --llvm --branch --ignore-not-existing \
-                --ignore "/*" --ignore "src/error.rs" \
+                --ignore "/*" \
                 --excl-line '#\[|=> panic!|unreachable!|Io\(std::io::Error\)|//!|///|^[ }]*$' \
                 --excl-br-line '#\[|=> panic!|unreachable!|assert_..!|//!|///' -o ./coverage/lcov.info
     - name: Send to Coveralls

src/error.rs

@@ -27,3 +27,17 @@ impl From<std::io::Error> for Error {
         }
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::Error;
+
+    #[test]
+    fn test_error() {
+        let err: Error = std::io::Error::from(std::io::ErrorKind::UnexpectedEof).into();
+        match err {
+            Error::TooShort => (),
+            _ => panic!("Unexpected error: not TooShort"),
+        }
+    }
+}