diff --git a/tests/load_from_source.rs b/tests/load_from_source.rs
new file mode 100644
index 00000000..109644cd
--- /dev/null
+++ b/tests/load_from_source.rs
@@ -0,0 +1,95 @@
+//! Integration tests for loading fonts from a non-filesystem FontSource.
+
+use std::collections::HashMap;
+use std::io;
+use std::path::{Path, PathBuf};
+
+use norad::{DataRequest, Font, FontSource};
+
+/// A simple in-memory source that wraps a HashMap.
+struct MemorySource(HashMap<PathBuf, Vec<u8>>);
+
+impl FontSource for MemorySource {
+    fn try_read(&self, path: &Path) -> Option<Result<Vec<u8>, io::Error>> {
+        self.0.get(path).cloned().map(Ok)
+    }
+}
+
+/// Build a MemorySource by walking a real UFO directory on disk.
+fn source_from_ufo_dir(ufo_path: &str) -> MemorySource {
+    let root = Path::new(ufo_path);
+    let mut map = HashMap::new();
+    walk_dir(root, root, &mut map);
+    MemorySource(map)
+}
+
+fn walk_dir(root: &Path, dir: &Path, map: &mut HashMap<PathBuf, Vec<u8>>) {
+    for entry in std::fs::read_dir(dir).unwrap() {
+        let entry = entry.unwrap();
+        let path = entry.path();
+        if path.is_dir() {
+            walk_dir(root, &path, map);
+        } else {
+            let rel = path.strip_prefix(root).unwrap().to_path_buf();
+            let contents = std::fs::read(&path).unwrap();
+            map.insert(rel, contents);
+        }
+    }
+}
+
+#[test]
+fn load_from_source_matches_filesystem() {
+    let ufo_path = "testdata/MutatorSansLightWide.ufo";
+    let source = source_from_ufo_dir(ufo_path);
+
+    let font_fs = Font::load(ufo_path).unwrap();
+    let font_src = Font::load_from_source(&DataRequest::all(), &source).unwrap();
+
+    // Core data should match
+    assert_eq!(font_fs.meta, font_src.meta);
+    assert_eq!(font_fs.font_info, font_src.font_info);
+    assert_eq!(font_fs.lib, font_src.lib);
+    assert_eq!(font_fs.groups, font_src.groups);
+    assert_eq!(font_fs.kerning, font_src.kerning);
+    assert_eq!(font_fs.features, font_src.features);
+
+    // Layers and glyphs
+    assert_eq!(font_fs.iter_layers().count(), font_src.iter_layers().count());
+    assert_eq!(font_fs.glyph_count(), font_src.glyph_count());
+    for layer_fs in font_fs.iter_layers() {
+        let layer_src = font_src.layers.get(layer_fs.name()).unwrap();
+        assert_eq!(layer_fs, layer_src, "layer '{}' mismatch", layer_fs.name());
+    }
+}
+
+#[test]
+fn load_from_source_with_closure() {
+    let ufo_path = "testdata/MutatorSansLightWide.ufo";
+    let source = source_from_ufo_dir(ufo_path);
+
+    let reader =
+        |path: &Path| -> Option<Result<Vec<u8>, io::Error>> { source.0.get(path).cloned().map(Ok) };
+    let font = Font::load_from_source(&DataRequest::all(), &reader).unwrap();
+
+    assert_eq!(font.glyph_count(), 48);
+}
+
+#[test]
+fn load_from_source_data_request_none() {
+    let ufo_path = "testdata/MutatorSansLightWide.ufo";
+    let source = source_from_ufo_dir(ufo_path);
+
+    let font = Font::load_from_source(&DataRequest::none(), &source).unwrap();
+
+    assert!(font.groups.is_empty());
+    assert!(font.kerning.is_empty());
+    assert!(font.features.is_empty());
+    assert!(font.default_layer().is_empty());
+}
+
+#[test]
+fn load_from_source_missing_metainfo() {
+    let source = MemorySource(HashMap::new());
+    let result = Font::load_from_source(&DataRequest::all(), &source);
+    assert!(result.is_err());
+}