Distinguish cargo_workspace input vie enum

This allows to skip the cargo workspace detection based on the value passed

insta/src/env.rs

@@ -430,23 +430,35 @@ pub fn snapshot_update_behavior(tool_config: &ToolConfig, unseen: bool) -> Snaps
     }
 }
 
+pub enum Workspace {
+    DetectWithCargo(&'static str),
+    UseAsIs(&'static str),
+}
+
 /// Returns the cargo workspace path for a crate manifest, like
 /// `/Users/janedoe/projects/insta` when passed
 /// `/Users/janedoe/projects/insta/insta/Cargo.toml`.
-pub fn get_cargo_workspace(manifest_dir: &str) -> Arc<PathBuf> {
-    // If INSTA_WORKSPACE_ROOT environment variable is set at runtime, use the value as-is.
-    // If INSTA_WORKSPACE_ROOT environment variable is set at compile time, use the value as-is.
-    // If INSTA_WORKSPACE_ROOT environment variable is not set, use `cargo metadata` to find the workspace root.
-    //
+///
+/// If `INSTA_WORKSPACE_ROOT` environment variable is set at runtime, use the value as-is.
+/// If `INSTA_WORKSPACE_ROOT` environment variable is set at compile time, use the value as-is.
+/// If `INSTA_WORKSPACE_ROOT` environment variable is not set, use `cargo metadata` to find the workspace root.
+pub fn get_cargo_workspace(workspace: Workspace) -> Arc<PathBuf> {
     // This is useful where CARGO_MANIFEST_DIR at compilation points to some
     // transient location. This can easily happen when building the test in one
     // directory but running it in another.
     if let Ok(workspace_root) = env::var("INSTA_WORKSPACE_ROOT") {
         return PathBuf::from(workspace_root).into();
-    } else if let Some(workspace_root) = option_env!("INSTA_WORKSPACE_ROOT") {
-        return PathBuf::from(workspace_root).into();
     }
 
+    // Distinguish if we need to run `cargo metadata`` or if we can return the workspace
+    // as is.
+    // This is useful if INSTA_WORKSPACE_ROOT was set at compile time, not pointing to
+    // the cargo manifest directory
+    let manifest_dir = match workspace {
+        Workspace::UseAsIs(workspace_root) => return PathBuf::from(workspace_root).into(),
+        Workspace::DetectWithCargo(manifest_dir) => manifest_dir,
+    };
+
     let error_message = || {
         format!(
             "`cargo metadata --format-version=1 --no-deps` in path `{}`",
@@ -497,12 +509,19 @@ pub fn get_cargo_workspace(manifest_dir: &str) -> Arc<PathBuf> {
 }
 
 #[test]
-fn test_get_cargo_workspace() {
-    let workspace = get_cargo_workspace(env!("CARGO_MANIFEST_DIR"));
+fn test_get_cargo_workspace_manifest_dir() {
+    let workspace = get_cargo_workspace(Workspace::DetectWithCargo(env!("CARGO_MANIFEST_DIR")));
     // The absolute path of the workspace, like `/Users/janedoe/projects/insta`
     assert!(workspace.ends_with("insta"));
 }
 
+#[test]
+fn test_get_cargo_workspace_insta_workspace() {
+    let workspace = get_cargo_workspace(Workspace::UseAsIs("/tmp/insta_workspace_root"));
+    // The absolute path of the workspace, like `/tmp/insta_workspace_root`
+    assert!(workspace.ends_with("insta_workspace_root"));
+}
+
 #[cfg(feature = "_cargo_insta_internal")]
 impl std::str::FromStr for TestRunner {
     type Err = ();

insta/src/lib.rs

@@ -345,7 +345,7 @@ pub use crate::redaction::{dynamic_redaction, rounded_redaction, sorted_redactio
 #[doc(hidden)]
 pub mod _macro_support {
     pub use crate::content::Content;
-    pub use crate::env::get_cargo_workspace;
+    pub use crate::env::{get_cargo_workspace, Workspace};
     pub use crate::runtime::{
         assert_snapshot, with_allow_duplicates, AutoName, BinarySnapshotValue, InlineValue,
         SnapshotValue,

insta/src/macros.rs

@@ -27,10 +27,10 @@ macro_rules! _get_workspace_root {
         // By default the `CARGO_MANIFEST_DIR` environment variable is used as the workspace root.
         // If the `INSTA_WORKSPACE_ROOT` environment variable is set at compile time it will override the default.
         // This can be useful to avoid including local paths in the binary.
-        const WORKSPACE_ROOT: &str = if let Some(root) = option_env!("INSTA_WORKSPACE_ROOT") {
-            root
+        const WORKSPACE_ROOT: $crate::_macro_support::Workspace = if let Some(root) = option_env!("INSTA_WORKSPACE_ROOT") {
+            $crate::_macro_support::Workspace::UseAsIs(root)
         } else {
-            env!("CARGO_MANIFEST_DIR")
+            $crate::_macro_support::Workspace::DetectWithCargo(env!("CARGO_MANIFEST_DIR"))
         };
         $crate::_macro_support::get_cargo_workspace(WORKSPACE_ROOT)
     }};