add bindings for git_branch_name_is_valid (#715)

Author: franciscod

Diff for: libgit2-sys/lib.rs

@@ -2740,6 +2740,7 @@ extern "C" {
         force: c_int,
     ) -> c_int;
     pub fn git_branch_name(out: *mut *const c_char, branch: *const git_reference) -> c_int;
+    pub fn git_branch_name_is_valid(valid: *mut c_int, name: *const c_char) -> c_int;
     pub fn git_branch_remote_name(
         out: *mut git_buf,
         repo: *mut git_repository,

Diff for: src/branch.rs

@@ -28,6 +28,16 @@ impl<'repo> Branch<'repo> {
         Branch { inner: reference }
     }
 
+    /// Ensure the branch name is well-formed.
+    pub fn name_is_valid(name: &str) -> Result<bool, Error> {
+        let name = CString::new(name)?;
+        let mut valid: libc::c_int = 0;
+        unsafe {
+            try_call!(raw::git_branch_name_is_valid(&mut valid, name.as_ptr()));
+        }
+        Ok(valid == 1)
+    }
+
     /// Gain access to the reference that is this branch
     pub fn get(&self) -> &Reference<'repo> {
         &self.inner
@@ -151,7 +161,7 @@ impl<'repo> Drop for Branches<'repo> {
 
 #[cfg(test)]
 mod tests {
-    use crate::BranchType;
+    use crate::{Branch, BranchType};
 
     #[test]
     fn smoke() {
@@ -175,4 +185,12 @@ mod tests {
 
         b1.delete().unwrap();
     }
+
+    #[test]
+    fn name_is_valid() {
+        assert!(Branch::name_is_valid("foo").unwrap());
+        assert!(!Branch::name_is_valid("").unwrap());
+        assert!(!Branch::name_is_valid("with spaces").unwrap());
+        assert!(!Branch::name_is_valid("~tilde").unwrap());
+    }
 }