diff --git a/gix/src/repository/mailmap.rs b/gix/src/repository/mailmap.rs
index 02921ec142e..ae725216857 100644
--- a/gix/src/repository/mailmap.rs
+++ b/gix/src/repository/mailmap.rs
@@ -1,7 +1,6 @@
 use crate::{Id, config::tree::Mailmap};
 
 impl crate::Repository {
-    // TODO: tests
     /// Similar to [`open_mailmap_into()`][crate::Repository::open_mailmap_into()], but ignores all errors and returns at worst
     /// an empty mailmap, e.g. if there is no mailmap or if there were errors loading them.
     ///
@@ -13,7 +12,6 @@ impl crate::Repository {
         out
     }
 
-    // TODO: tests
     /// Try to merge mailmaps from the following locations into `target`:
     ///
     /// - read the `.mailmap` file without following symlinks from the working tree, if present
diff --git a/gix/tests/fixtures/generated-archives/make_mailmap_repo.tar b/gix/tests/fixtures/generated-archives/make_mailmap_repo.tar
new file mode 100644
index 00000000000..ec9434becb8
Binary files /dev/null and b/gix/tests/fixtures/generated-archives/make_mailmap_repo.tar differ
diff --git a/gix/tests/fixtures/generated-archives/make_mailmap_repo_sha256.tar b/gix/tests/fixtures/generated-archives/make_mailmap_repo_sha256.tar
new file mode 100644
index 00000000000..c755fc473cf
Binary files /dev/null and b/gix/tests/fixtures/generated-archives/make_mailmap_repo_sha256.tar differ
diff --git a/gix/tests/fixtures/make_mailmap_repo.sh b/gix/tests/fixtures/make_mailmap_repo.sh
new file mode 100755
index 00000000000..16ad37d3d27
--- /dev/null
+++ b/gix/tests/fixtures/make_mailmap_repo.sh
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -eu -o pipefail
+
+git init -q
+git checkout -b main
+
+git config user.name "Committer"
+git config user.email "committer@example.com"
+git config commit.gpgsign false
+
+# A .mailmap that remaps an author's display name by email.
+# Format: <Proper Name> <commit@email>
+cat >.mailmap <<'EOF'
+Proper Name <proper@example.com>
+EOF
+
+touch a
+git add a .mailmap
+git commit -q -m "initial with mailmap"
diff --git a/gix/tests/gix/repository/mailmap.rs b/gix/tests/gix/repository/mailmap.rs
new file mode 100644
index 00000000000..4b22f931409
--- /dev/null
+++ b/gix/tests/gix/repository/mailmap.rs
@@ -0,0 +1,55 @@
+use gix_date::parse::TimeBuf;
+
+use crate::{Result, named_repo};
+
+fn signature(name: &str, email: &str) -> gix_actor::Signature {
+    gix_actor::Signature {
+        name: name.into(),
+        email: email.into(),
+        time: gix_date::parse_header("42 +0800").expect("static input parses"),
+    }
+}
+
+#[test]
+fn empty_when_no_mailmap_present() -> Result {
+    let repo = named_repo("make_basic_repo.sh")?;
+    let snapshot = repo.open_mailmap();
+    assert!(
+        snapshot.entries().is_empty(),
+        "a repo without any .mailmap or mailmap.* config yields an empty snapshot"
+    );
+
+    let mut into = gix_mailmap::Snapshot::default();
+    repo.open_mailmap_into(&mut into)
+        .expect("with no mailmap sources, no IO error is collected");
+    assert!(
+        into.entries().is_empty(),
+        "open_mailmap_into mirrors open_mailmap when there are no sources"
+    );
+    Ok(())
+}
+
+#[test]
+fn reads_mailmap_from_worktree_root() -> Result {
+    let repo = named_repo("make_mailmap_repo.sh")?;
+    let snapshot = repo.open_mailmap();
+    assert_eq!(
+        snapshot.entries().len(),
+        1,
+        "the single entry from the worktree .mailmap is loaded"
+    );
+
+    let mut buf = TimeBuf::default();
+    let resolved = snapshot
+        .try_resolve(signature("Old Name", "proper@example.com").to_ref(&mut buf))
+        .expect("the entry rewrites the display name when the email matches");
+    assert_eq!(
+        resolved.name, "Proper Name",
+        "the mapped name from .mailmap replaces the original"
+    );
+    assert_eq!(
+        resolved.email, "proper@example.com",
+        "the email is preserved (this entry only changes the name)"
+    );
+    Ok(())
+}
diff --git a/gix/tests/gix/repository/mod.rs b/gix/tests/gix/repository/mod.rs
index f60ad9e4192..53d9fa9d455 100644
--- a/gix/tests/gix/repository/mod.rs
+++ b/gix/tests/gix/repository/mod.rs
@@ -11,6 +11,8 @@ mod config;
 mod excludes;
 #[cfg(feature = "attributes")]
 mod filter;
+#[cfg(feature = "mailmap")]
+mod mailmap;
 #[cfg(feature = "merge")]
 mod merge;
 mod object;