Add tests

tests/test.rs

@@ -0,0 +1,69 @@
+use serde::Deserialize;
+use serde_derive::Deserialize;
+use std::collections::{BTreeMap as Map, BTreeSet as Set};
+use std::iter::FromIterator;
+
+fn assert_ignored<'de, T>(json: &'de str, expected: &[&str]) -> T
+where
+    T: Deserialize<'de>,
+{
+    let de = &mut serde_json::Deserializer::from_str(json);
+
+    let mut unused = Set::new();
+
+    let value: T = serde_ignored::deserialize(de, |path| {
+        unused.insert(path.to_string());
+    })
+    .unwrap();
+
+    let expected = Set::from_iter(expected.into_iter().cloned().map(str::to_owned));
+    assert_eq!(unused, expected);
+
+    value
+}
+
+#[test]
+fn test_readme() {
+    #[derive(Debug, PartialEq, Deserialize)]
+    struct Package {
+        name: String,
+        dependencies: Map<String, Dependency>,
+    }
+
+    #[derive(Debug, PartialEq, Deserialize)]
+    struct Dependency {
+        version: String,
+    }
+
+    let json = r#"{
+        "name": "demo",
+        "dependencies": {
+            "serde": {
+                "version": "0.9",
+                "typo1": ""
+            }
+        },
+        "typo2": {
+            "inner": ""
+        },
+        "typo3": {}
+    }"#;
+
+    let ignored = &["dependencies.serde.typo1", "typo2", "typo3"];
+    let p: Package = assert_ignored(json, ignored);
+
+    let expected = Package {
+        name: "demo".to_owned(),
+        dependencies: {
+            let mut map = Map::new();
+            map.insert(
+                "serde".to_owned(),
+                Dependency {
+                    version: "0.9".to_owned(),
+                },
+            );
+            map
+        },
+    };
+    assert_eq!(p, expected);
+}