diff --git a/satrs-core/src/cfdp/filestore.rs b/satrs-core/src/cfdp/filestore.rs
index 72fdb4e..3a840c1 100644
--- a/satrs-core/src/cfdp/filestore.rs
+++ b/satrs-core/src/cfdp/filestore.rs
@@ -98,7 +98,8 @@ pub trait VirtualFilestore {
     /// This can be more efficient than removing and re-creating a file.
     fn truncate_file(&self, file_path: &str) -> Result<(), FilestoreError>;
 
-    fn remove_dir(&self, file_path: &str, all: bool) -> Result<(), FilestoreError>;
+    fn remove_dir(&self, dir_path: &str, all: bool) -> Result<(), FilestoreError>;
+    fn create_dir(&self, dir_path: &str) -> Result<(), FilestoreError>;
 
     fn read_data(
         &self,
@@ -155,7 +156,7 @@ pub mod stdmod {
 
         fn remove_file(&self, file_path: &str) -> Result<(), FilestoreError> {
             if !self.exists(file_path) {
-                return Ok(());
+                return Err(FilestoreError::FileDoesNotExist);
             }
             if !self.is_file(file_path) {
                 return Err(FilestoreError::IsNotFile);
@@ -166,7 +167,7 @@ pub mod stdmod {
 
         fn truncate_file(&self, file_path: &str) -> Result<(), FilestoreError> {
             if !self.exists(file_path) {
-                return Ok(());
+                return Err(FilestoreError::FileDoesNotExist);
             }
             if !self.is_file(file_path) {
                 return Err(FilestoreError::IsNotFile);
@@ -178,6 +179,14 @@ pub mod stdmod {
             Ok(())
         }
 
+        fn create_dir(&self, dir_path: &str) -> Result<(), FilestoreError> {
+            fs::create_dir(dir_path).map_err(|e| FilestoreError::Io {
+                raw_errno: e.raw_os_error(),
+                string: e.to_string(),
+            })?;
+            Ok(())
+        }
+
         fn remove_dir(&self, dir_path: &str, all: bool) -> Result<(), FilestoreError> {
             if !self.exists(dir_path) {
                 return Err(FilestoreError::DirDoesNotExist);
@@ -316,7 +325,7 @@ mod tests {
     }
 
     #[test]
-    fn test_basic_native_fs_exists() {
+    fn test_basic_native_fs_file_exists() {
         let tmpdir = tempdir().expect("creating tmpdir failed");
         let file_path = tmpdir.path().join("test.txt");
         assert!(!NATIVE_FS.exists(file_path.to_str().unwrap()));
@@ -328,6 +337,34 @@ mod tests {
         fs::remove_dir_all(tmpdir).expect("clearing tmpdir failed");
     }
 
+    #[test]
+    fn test_basic_native_fs_dir_exists() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let dir_path = tmpdir.path().join("testdir");
+        assert!(!NATIVE_FS.exists(dir_path.to_str().unwrap()));
+        NATIVE_FS
+            .create_dir(dir_path.to_str().expect("getting str for file failed"))
+            .unwrap();
+        assert!(NATIVE_FS.exists(dir_path.to_str().unwrap()));
+        assert!(NATIVE_FS.is_dir(dir_path.as_path().to_str().unwrap()));
+        fs::remove_dir_all(tmpdir).expect("clearing tmpdir failed");
+    }
+
+    #[test]
+    fn test_basic_native_fs_remove_file() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let file_path = tmpdir.path().join("test.txt");
+        NATIVE_FS
+            .create_file(file_path.to_str().expect("getting str for file failed"))
+            .expect("creating file failed");
+        assert!(NATIVE_FS.exists(file_path.to_str().unwrap()));
+        NATIVE_FS
+            .remove_file(file_path.to_str().unwrap())
+            .expect("removing file failed");
+        assert!(!NATIVE_FS.exists(file_path.to_str().unwrap()));
+        fs::remove_dir_all(tmpdir).expect("clearing tmpdir failed");
+    }
+
     #[test]
     fn test_basic_native_fs_write() {
         let tmpdir = tempdir().expect("creating tmpdir failed");
@@ -367,4 +404,110 @@ mod tests {
         assert_eq!(read_back, write_data);
         fs::remove_dir_all(tmpdir).expect("clearing tmpdir failed");
     }
+
+    #[test]
+    fn test_truncate_file() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let file_path = tmpdir.path().join("test.txt");
+        NATIVE_FS
+            .create_file(file_path.to_str().expect("getting str for file failed"))
+            .expect("creating file failed");
+        fs::write(file_path.clone(), [1, 2, 3, 4]).unwrap();
+        assert_eq!(fs::read(file_path.clone()).unwrap(), [1, 2, 3, 4]);
+        NATIVE_FS
+            .truncate_file(file_path.to_str().unwrap())
+            .unwrap();
+        assert_eq!(fs::read(file_path.clone()).unwrap(), []);
+        fs::remove_dir_all(tmpdir).expect("clearing tmpdir failed");
+    }
+
+    #[test]
+    fn test_remove_dir() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let dir_path = tmpdir.path().join("testdir");
+        assert!(!NATIVE_FS.exists(dir_path.to_str().unwrap()));
+        NATIVE_FS
+            .create_dir(dir_path.to_str().expect("getting str for file failed"))
+            .unwrap();
+        assert!(NATIVE_FS.exists(dir_path.to_str().unwrap()));
+        NATIVE_FS
+            .remove_dir(dir_path.to_str().unwrap(), false)
+            .unwrap();
+        assert!(!NATIVE_FS.exists(dir_path.to_str().unwrap()));
+        fs::remove_dir_all(tmpdir).expect("clearing tmpdir failed");
+    }
+
+    #[test]
+    fn test_read_file() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let file_path = tmpdir.path().join("test.txt");
+        NATIVE_FS
+            .create_file(file_path.to_str().expect("getting str for file failed"))
+            .expect("creating file failed");
+        fs::write(file_path.clone(), [1, 2, 3, 4]).unwrap();
+        let read_buf: &mut [u8] = &mut [0; 4];
+        NATIVE_FS
+            .read_data(file_path.to_str().unwrap(), 0, 4, read_buf)
+            .unwrap();
+        assert_eq!([1, 2, 3, 4], read_buf);
+        NATIVE_FS
+            .write_data(file_path.to_str().unwrap(), 4, &[5, 6, 7, 8])
+            .expect("writing to file failed");
+        NATIVE_FS
+            .read_data(file_path.to_str().unwrap(), 2, 4, read_buf)
+            .unwrap();
+        assert_eq!([3, 4, 5, 6], read_buf);
+    }
+
+    #[test]
+    fn test_remove_which_does_not_exist() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let file_path = tmpdir.path().join("test.txt");
+        let result = NATIVE_FS.read_data(file_path.to_str().unwrap(), 0, 4, &mut [0; 4]);
+        assert!(result.is_err());
+        let error = result.unwrap_err();
+        if let FilestoreError::FileDoesNotExist = error {
+            assert_eq!(error.to_string(), "file does not exist");
+        } else {
+            panic!("unexpected error");
+        }
+    }
+
+    #[test]
+    fn test_file_already_exists() {
+        let tmpdir = tempdir().expect("creating tmpdir failed");
+        let file_path = tmpdir.path().join("test.txt");
+        let result =
+            NATIVE_FS.create_file(file_path.to_str().expect("getting str for file failed"));
+        assert!(result.is_ok());
+        let result =
+            NATIVE_FS.create_file(file_path.to_str().expect("getting str for file failed"));
+        assert!(result.is_err());
+        let error = result.unwrap_err();
+        if let FilestoreError::FileAlreadyExists = error {
+            assert_eq!(error.to_string(), "file already exists");
+        } else {
+            panic!("unexpected error");
+        }
+    }
+
+    #[test]
+    fn test_remove_file_with_dir_api() {
+        // TODO
+    }
+
+    #[test]
+    fn test_remove_dir_with_file_api() {
+        // TODO
+    }
+
+    #[test]
+    fn test_remove_dir_which_does_not_exist() {
+        // TODO
+    }
+
+    #[test]
+    fn test_byte_conversion_error_when_reading() {
+        // TODO
+    }
 }