Port tests from apache/avro test_schema.py and implement schema equal…

…ity based on parsing canonical form (#97)

I noticed that we were deriving PartialEq for Schema while my understanding
is that the spec asserts that equality between schemas has to rely on
parsing canonical form. So I manually impemented PartialEq and Eq based
on that.

I also created a bunch of issues to follow with the tests that I had to
comment because they were failing.

src/reader.rs

@@ -400,7 +400,7 @@ mod tests {
     #[test]
     fn test_reader_empty_buffer() {
         let empty = Cursor::new(Vec::new());
-        Reader::new(empty).is_err();
+        assert!(Reader::new(empty).is_err());
     }
 
     #[test]

src/schema.rs

@@ -7,7 +7,7 @@ use digest::Digest;
 use failure::{Error, Fail};
 use serde::{
     ser::{SerializeMap, SerializeSeq},
-    Serialize, Serializer,
+    Deserialize, Serialize, Serializer,
 };
 use serde_json::{self, Map, Value};
 
@@ -52,7 +52,7 @@ impl fmt::Display for SchemaFingerprint {
 /// Represents any valid Avro schema
 /// More information about Avro schemas can be found in the
 /// [Avro Specification](https://avro.apache.org/docs/current/spec.html#schemas)
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug)]
 pub enum Schema {
     /// A `null` Avro schema.
     Null,
@@ -101,6 +101,18 @@ pub enum Schema {
     Fixed { name: Name, size: usize },
 }
 
+impl PartialEq for Schema {
+    /// Assess equality of two `Schema` based on [Parsing Canonical Form].
+    ///
+    /// [Parsing Canonical Form]:
+    /// https://avro.apache.org/docs/1.8.2/spec.html#Parsing+Canonical+Form+for+Schemas
+    fn eq(&self, other: &Self) -> bool {
+        self.canonical_form() == other.canonical_form()
+    }
+}
+
+impl Eq for Schema {}
+
 /// This type is used to simplify enum variant comparison between `Schema` and `types::Value`.
 /// It may have utility as part of the public API, but defining as `pub(crate)` for now.
 ///
@@ -182,7 +194,7 @@ impl<'a> From<&'a types::Value> for SchemaKind {
 ///
 /// More information about schema names can be found in the
 /// [Avro specification](https://avro.apache.org/docs/current/spec.html#names)
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq, Deserialize)]
 pub struct Name {
     pub name: String,
     pub namespace: Option<String>,
@@ -380,6 +392,7 @@ impl PartialEq for UnionSchema {
 impl Schema {
     /// Create a `Schema` from a string representing a JSON Avro schema.
     pub fn parse_str(input: &str) -> Result<Self, Error> {
+        // TODO: (#82) this should be a ParseSchemaError wrapping the JSON error
         let value = serde_json::from_str(input)?;
         Self::parse(&value)
     }
@@ -981,5 +994,4 @@ mod tests {
             format!("{}", schema.fingerprint::<Md5>())
         );
     }
-
 }

tests/io.rs

@@ -1,4 +1,4 @@
-//! Port of https://github.com/apache/avro/blob/master/lang/py/test/test_io.py
+//! Port of https://github.com/apache/avro/blob/release-1.9.1/lang/py/test/test_io.py
 use std::io::Cursor;
 
 use avro_rs::{
@@ -40,15 +40,19 @@ lazy_static! {
         (r#""null""#, "null", Value::Null),
         (r#""boolean""#, "true", Value::Boolean(true)),
         (r#""string""#, r#""foo""#, Value::String("foo".to_string())),
+        // TODO: (#96) investigate why this is failing
         //(r#""bytes""#, r#""\u00FF\u00FF""#, Value::Bytes(vec![0xff, 0xff])),
         (r#""int""#, "5", Value::Int(5)),
         (r#""long""#, "5", Value::Long(5)),
         (r#""float""#, "1.1", Value::Float(1.1)),
         (r#""double""#, "1.1", Value::Double(1.1)),
+        // TODO: (#96) investigate why this is failing
         //(r#"{"type": "fixed", "name": "F", "size": 2}"#, r#""\u00FF\u00FF""#, Value::Bytes(vec![0xff, 0xff])),
+        // TODO: (#96) investigate why this is failing
         //(r#"{"type": "enum", "name": "F", "symbols": ["FOO", "BAR"]}"#, r#""FOO""#, Value::Enum(0, "FOO".to_string())),
         (r#"{"type": "array", "items": "int"}"#, "[1, 2, 3]", Value::Array(vec![Value::Int(1), Value::Int(2), Value::Int(3)])),
         (r#"{"type": "map", "values": "int"}"#, r#"{"a": 1, "b": 2}"#, Value::Map([("a".to_string(), Value::Int(1)), ("b".to_string(), Value::Int(2))].iter().cloned().collect())),
+        // TODO: (#96) investigate why this is failing
         //(r#"["int", "null"]"#, "5", Value::Union(Box::new(Value::Int(5)))),
         (r#"{"type": "record", "name": "F", "fields": [{"name": "A", "type": "int"}]}"#, r#"{"A": 5}"#,Value::Record(vec![("A".to_string(), Value::Int(5))])),
     ];