Use TryInto for more permissive deserialization for integers

* Attempt to convert between integer types using `TryInto`-based
conversions rather than blanket failing for some source and
destination types.
* Use `into_uint` instead of `into_int` in `Value` Deserialize
implementations for unsigned integer types. Previously, we were
converting from signed types to unsigned types using `as`, which can
lead to surprise integer values conversions (#93).

Fixes #352 and #93

1 files changed, 73 insertions, 0 deletions

diff --git a/tests/env.rs b/tests/env.rs
index ad252e4..2ee67de 100644
--- a/tests/env.rs
+++ b/tests/env.rs
@@ -131,6 +131,39 @@ fn test_parse_int() {
 }
 
 #[test]
+fn test_parse_uint() {
+    // using a struct in an enum here to make serde use `deserialize_any`
+    #[derive(Deserialize, Debug)]
+    #[serde(tag = "tag")]
+    enum TestUintEnum {
+        Uint(TestUint),
+    }
+
+    #[derive(Deserialize, Debug)]
+    struct TestUint {
+        int_val: u32,
+    }
+
+    temp_env::with_var("INT_VAL", Some("42"), || {
+        let environment = Environment::default().try_parsing(true);
+
+        let config = Config::builder()
+            .set_default("tag", "Uint")
+            .unwrap()
+            .add_source(environment)
+            .build()
+            .unwrap();
+
+        let config: TestUintEnum = config.try_deserialize().unwrap();
+
+        assert!(matches!(
+            config,
+            TestUintEnum::Uint(TestUint { int_val: 42 })
+        ));
+    })
+}
+
+#[test]
 fn test_parse_float() {
     // using a struct in an enum here to make serde use `deserialize_any`
     #[derive(Deserialize, Debug)]
@@ -535,3 +568,43 @@ fn test_parse_off_string() {
         }
     })
 }
+
+#[test]
+fn test_parse_int_default() {
+    #[derive(Deserialize, Debug)]
+    struct TestInt {
+        int_val: i32,
+    }
+
+    let environment = Environment::default().try_parsing(true);
+
+    let config = Config::builder()
+        .set_default("int_val", 42_i32)
+        .unwrap()
+        .add_source(environment)
+        .build()
+        .unwrap();
+
+    let config: TestInt = config.try_deserialize().unwrap();
+    assert_eq!(config.int_val, 42);
+}
+
+#[test]
+fn test_parse_uint_default() {
+    #[derive(Deserialize, Debug)]
+    struct TestUint {
+        int_val: u32,
+    }
+
+    let environment = Environment::default().try_parsing(true);
+
+    let config = Config::builder()
+        .set_default("int_val", 42_u32)
+        .unwrap()
+        .add_source(environment)
+        .build()
+        .unwrap();
+
+    let config: TestUint = config.try_deserialize().unwrap();
+    assert_eq!(config.int_val, 42);
+}