fix: fix availability check + test

Signed-off-by: Yato202010 <61349049+Yato202010@users.noreply.github.com>

src/os/linux/fuseoverlay.rs

@@ -152,6 +152,13 @@ impl FuseOverlayFs {
 impl Filesystem for FuseOverlayFs {
     #[inline]
     fn mount(&mut self) -> Result<PathBuf> {
+        #[cfg(not(feature = "fuse-overlayfs-vendored"))]
+        if !Self::is_available() {
+            return Err(Error::new(
+                ErrorKind::NotFound,
+                "fuse-overlayfs is not available",
+            ));
+        }
         if matches!(self.id,Some(x) if x == PartitionID::try_from(self.target.as_path())?) {
             debug!("Damascus: partition already mounted");
             return Ok(PathBuf::from(&self.target.as_path()));
@@ -480,10 +487,10 @@ impl Drop for FuseOverlayFs {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-
+    #[cfg(feature = "fuse-overlayfs-vendored")]
     #[test]
     fn availability() {
+        use super::{Filesystem, FuseOverlayFs};
         assert!(FuseOverlayFs::is_available())
     }
 }

src/os/linux/overlay.rs

@@ -143,6 +143,12 @@ impl OverlayFs {
 impl Filesystem for OverlayFs {
     #[inline]
     fn mount(&mut self) -> Result<PathBuf> {
+        if !Self::is_available() {
+            return Err(Error::new(
+                ErrorKind::NotFound,
+                "overlayfs is not available",
+            ));
+        }
         if matches!(self.id,Some(x) if x == PartitionID::try_from(self.target.as_path())?) {
             debug!("Damascus: partition already mounted");
             return Ok(self.target.as_path().to_path_buf());
@@ -377,13 +383,3 @@ impl Drop for OverlayFs {
         }
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn availability() {
-        assert!(OverlayFs::is_available())
-    }
-}

src/os/linux/unionfs_fuse.rs

@@ -106,6 +106,13 @@ impl UnionFsFuse {
 impl Filesystem for UnionFsFuse {
     #[inline]
     fn mount(&mut self) -> Result<PathBuf> {
+        #[cfg(not(feature = "unionfs-fuse-vendored"))]
+        if !Self::is_available() {
+            return Err(Error::new(
+                ErrorKind::NotFound,
+                "unionfs-fuse is not available",
+            ));
+        }
         if matches!(self.id,Some(x) if x == PartitionID::try_from(self.target.as_path())?) {
             debug!("Damascus: partition already mounted");
             return Ok(PathBuf::from(&self.target.as_path()));
@@ -342,10 +349,10 @@ impl Drop for UnionFsFuse {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-
+    #[cfg(feature = "unionfs-fuse-vendored")]
     #[test]
     fn availability() {
+        use super::{Filesystem, UnionFsFuse};
         assert!(UnionFsFuse::is_available())
     }
 }

tests/linux/unionfs_fuse.rs

@@ -7,6 +7,10 @@ use std::fs::create_dir_all;
 use temp_testdir::TempDir;
 
 pub fn mount_unionfs_fuse_r() {
+    if !UnionFsFuse::is_available() {
+        skip!("UnionFsFuse is not available");
+        return;
+    }
     if geteuid().is_root() {
         skip!("fuse mount can't be tested as root");
         return;
@@ -26,6 +30,10 @@ pub fn mount_unionfs_fuse_r() {
 }
 
 pub fn mount_unionfs_fuse_rw() {
+    if !UnionFsFuse::is_available() {
+        skip!("UnionFsFuse is not available");
+        return;
+    }
     if geteuid().is_root() {
         skip!("fuse mount can't be tested as root");
         return;
@@ -51,6 +59,10 @@ pub fn mount_unionfs_fuse_rw() {
 }
 
 pub fn mount_unionfs_fuse_rw_on_lower() {
+    if !UnionFsFuse::is_available() {
+        skip!("UnionFsFuse is not available");
+        return;
+    }
     if geteuid().is_root() {
         skip!("fuse mount can't be tested as root");
         return;