able to use version specified in .anchorversion

avm/src/lib.rs

@@ -45,10 +45,15 @@ pub fn version_binary_path(version: &Version) -> PathBuf {
 }
 
 /// Update the current version to a new version
-pub fn use_version(version: &Version) -> Result<()> {
+pub fn use_version(opt_version: Option<Version>) -> Result<()> {
+    let version = match opt_version {
+        Some(version) => version,
+        None => read_anchorversion_file()?
+    };
+
     let installed_versions = read_installed_versions();
     // Make sure the requested version is installed
-    if !installed_versions.contains(version) {
+    if !installed_versions.contains(&version) {
         if let Ok(current) = current_version() {
             println!("Version {version} is not installed, staying on version {current}.");
         } else {
@@ -118,7 +123,7 @@ pub fn install_version(version: &Version, force: bool) -> Result<()> {
         current_version_file.write_all(version.to_string().as_bytes())?;
     }
 
-    use_version(version)
+    use_version(Some(version.clone()))
 }
 
 /// Remove an installed version of anchor-cli
@@ -134,6 +139,14 @@ pub fn uninstall_version(version: &Version) -> Result<()> {
     Ok(())
 }
 
+/// Read version from .anchorversion
+pub fn read_anchorversion_file() -> Result<Version> {
+    fs::read_to_string(".anchorversion")
+    .map_err(|e| anyhow!(".anchorversion file not found: {e}"))
+    .map(|content| Version::parse(content.trim()))?
+    .map_err(|e| anyhow!("Unable to parse version: {e}"))
+} 
+
 /// Ensure the users home directory is setup with the paths required by AVM.
 pub fn ensure_paths() {
     let home_dir = AVM_HOME.to_path_buf();
@@ -239,6 +252,29 @@ mod tests {
     use semver::Version;
     use std::fs;
     use std::io::Write;
+    use std::env;
+
+    #[test]
+    fn test_read_anchorversion() {
+        ensure_paths();
+        let mut dir = env::current_dir().unwrap();
+        dir.push(".anchorversion");
+        let mut file_created = fs::File::create(&dir).unwrap();
+        let test_version = "0.26.0";
+        file_created.write(test_version.as_bytes()).unwrap();
+
+
+        let version = read_anchorversion_file();
+        match version {
+            Ok(v) => {
+                assert_eq!(v.to_string(), test_version);
+            },
+            Err(_e) => {
+                assert!(false);
+            }
+        }
+        fs::remove_file(&dir).unwrap();
+    }
 
     #[test]
     fn test_ensure_paths() {

avm/src/main.rs

@@ -1,4 +1,5 @@
 use anyhow::{Error, Result};
+use avm;
 use clap::{Parser, Subcommand};
 use semver::Version;
 
@@ -15,8 +16,8 @@ pub struct Cli {
 pub enum Commands {
     #[clap(about = "Use a specific version of Anchor")]
     Use {
-        #[clap(value_parser = parse_version)]
-        version: Version,
+        #[clap(value_parser = parse_version, required = false)]
+        version: Option<Version>,
     },
     #[clap(about = "Install a version of Anchor")]
     Install {
@@ -48,7 +49,7 @@ fn parse_version(version: &str) -> Result<Version, Error> {
 }
 pub fn entry(opts: Cli) -> Result<()> {
     match opts.command {
-        Commands::Use { version } => avm::use_version(&version),
+        Commands::Use { version } => avm::use_version(version),
         Commands::Install { version, force } => avm::install_version(&version, force),
         Commands::Uninstall { version } => avm::uninstall_version(&version),
         Commands::List {} => avm::list_versions(),