From c96c85872307d43180da57bde687136caa82d312 Mon Sep 17 00:00:00 2001
From: Jessica Black <me@jessica.black>
Date: Mon, 21 Apr 2025 11:04:06 -0700
Subject: [PATCH] Add `Locator::try_promote_strict` method (#22)

---
 Cargo.toml     |  2 +-
 src/locator.rs | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 65c21e8..35d6e4e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "locator"
-version = "2.4.0"
+version = "2.4.1"
 edition = "2024"
 
 [dependencies]
diff --git a/src/locator.rs b/src/locator.rs
index 9405b81..78569f8 100644
--- a/src/locator.rs
+++ b/src/locator.rs
@@ -247,6 +247,23 @@ impl Locator {
         })
     }
 
+    /// Promote a `Locator` to a [`StrictLocator`] if it has a `revision` component;
+    /// if not this function returns `Err` with the original locator.
+    pub fn try_promote_strict(self) -> Result<StrictLocator, Self> {
+        let locator = match self.revision {
+            None => return Err(self),
+            Some(rev) => StrictLocator::builder()
+                .fetcher(self.fetcher)
+                .package(self.package)
+                .revision(rev),
+        };
+
+        Ok(match self.org_id {
+            None => locator.build(),
+            Some(OrgId(id)) => locator.org_id(id).build(),
+        })
+    }
+
     /// Promote a `Locator` to a [`StrictLocator`] by providing the default value to use
     /// for the `revision` component, if one is not specified in the locator already.
     ///
@@ -732,6 +749,7 @@ mod tests {
         let promoted = input.clone().promote_strict_with(|| String::from("bar"));
         assert_eq!(expected, promoted, "promote {input}");
     }
+
     #[test]
     fn promotes_strict_existing_lazy() {
         let input = Locator::builder()
@@ -754,6 +772,39 @@ mod tests {
         assert_eq!(expected, promoted, "promote {input}");
     }
 
+    #[test]
+    fn try_promote_strict_with_revision() {
+        let input = Locator::builder()
+            .fetcher(Fetcher::Custom)
+            .package("foo")
+            .revision("1234")
+            .org_id(1)
+            .build();
+
+        let expected = StrictLocator::builder()
+            .fetcher(Fetcher::Custom)
+            .package("foo")
+            .org_id(1)
+            .revision("1234")
+            .build();
+
+        let result = input.try_promote_strict().expect("must promote strict");
+        assert_eq!(expected, result);
+    }
+
+    #[test]
+    fn try_promote_strict_without_revision() {
+        let input = Locator::builder()
+            .fetcher(Fetcher::Custom)
+            .package("foo")
+            .org_id(1)
+            .build();
+
+        input
+            .try_promote_strict()
+            .expect_err("must fail to promote");
+    }
+
     #[test]
     fn ordering() {
         let locators = vec![