allow space in SUMMARY.md's link destination

Author: Evian-Zhang

src/book/summary.rs

@@ -333,6 +333,7 @@ impl<'a> SummaryParser<'a> {
 
     /// Finishes parsing a link once the `Event::Start(Tag::Link(..))` has been opened.
     fn parse_link(&mut self, href: String) -> Link {
+        let href = href.replace("%20", " ").replace("+", " ");
         let link_content = collect_events!(self.stream, end Tag::Link(..));
         let name = stringify_events(link_content);
 
@@ -947,4 +948,35 @@ mod tests {
 
         assert_eq!(got, should_be);
     }
+    
+    #[test]
+    fn allow_space_in_link_destination() {
+        let src = "- [test1](./test%20link1.md)\n- [test2](./test+link2.md)\n- [test3](<./test link3.md>)";
+        let should_be = vec![
+            SummaryItem::Link(Link {
+                name: String::from("test1"),
+                location: Some(PathBuf::from("./test link1.md")),
+                number: Some(SectionNumber(vec![1])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Link(Link {
+                name: String::from("test2"),
+                location: Some(PathBuf::from("./test link2.md")),
+                number: Some(SectionNumber(vec![2])),
+                nested_items: Vec::new(),
+            }),
+            SummaryItem::Link(Link {
+                name: String::from("test3"),
+                location: Some(PathBuf::from("./test link3.md")),
+                number: Some(SectionNumber(vec![3])),
+                nested_items: Vec::new(),
+            }),
+        ];
+        let mut parser = SummaryParser::new(src);
+        let got = parser
+            .parse_numbered(&mut 0, &mut SectionNumber::default())
+            .unwrap();
+        
+        assert_eq!(got, should_be);
+    }
 }