auto merge of #10625 : huonw/rust/json-errors, r=alexcrichton
Fixes #4244.
This commit is contained in:
bors
commit
ce45bb7f44
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@ -804,7 +804,7 @@ impl<T : Iterator<char>> Parser<T> {
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while !self.eof() {
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self.parse_whitespace();
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if self.ch != '"' {
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if self.ch != '\"' {
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return self.error(~"key must be a string");
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}
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@ -866,12 +866,34 @@ pub fn Decoder(json: Json) -> Decoder {
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}
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}
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impl Decoder {
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fn err(&self, msg: &str) -> ! {
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fail!("JSON decode error: {}", msg);
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}
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fn missing_field(&self, field: &str, object: ~Object) -> ! {
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self.err(format!("missing required '{}' field in object: {}",
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field, Object(object).to_str()))
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}
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fn expected(&self, expected: &str, found: &Json) -> ! {
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let found_s = match *found {
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Null => "null",
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List(*) => "list",
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Object(*) => "object",
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Number(*) => "number",
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String(*) => "string",
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Boolean(*) => "boolean"
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};
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self.err(format!("expected {expct} but found {fnd}: {val}",
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expct=expected, fnd=found_s, val=found.to_str()))
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}
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}
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impl serialize::Decoder for Decoder {
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fn read_nil(&mut self) -> () {
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debug!("read_nil");
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match self.stack.pop() {
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Null => (),
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value => fail!("not a null: {:?}", value)
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value => self.expected("null", &value)
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}
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}
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@ -891,7 +913,7 @@ impl serialize::Decoder for Decoder {
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debug!("read_bool");
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match self.stack.pop() {
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Boolean(b) => b,
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value => fail!("not a boolean: {:?}", value)
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value => self.expected("boolean", &value)
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}
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}
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@ -899,25 +921,30 @@ impl serialize::Decoder for Decoder {
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debug!("read_f64");
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match self.stack.pop() {
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Number(f) => f,
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value => fail!("not a number: {:?}", value)
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value => self.expected("number", &value)
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}
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}
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fn read_f32(&mut self) -> f32 { self.read_f64() as f32 }
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fn read_f32(&mut self) -> f32 { self.read_f64() as f32 }
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fn read_char(&mut self) -> char {
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let mut v = ~[];
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let s = self.read_str();
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for c in s.iter() { v.push(c) }
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if v.len() != 1 { fail!("string must have one character") }
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v[0]
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{
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let mut it = s.iter();
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match (it.next(), it.next()) {
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// exactly one character
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(Some(c), None) => return c,
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_ => ()
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}
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}
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self.expected("single character string", &String(s))
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}
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fn read_str(&mut self) -> ~str {
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debug!("read_str");
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match self.stack.pop() {
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String(s) => s,
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json => fail!("not a string: {:?}", json)
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value => self.expected("string", &value)
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}
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}
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@ -933,26 +960,34 @@ impl serialize::Decoder for Decoder {
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debug!("read_enum_variant(names={:?})", names);
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let name = match self.stack.pop() {
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String(s) => s,
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Object(o) => {
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let n = match o.find(&~"variant").expect("invalidly encoded json") {
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&String(ref s) => s.clone(),
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_ => fail!("invalidly encoded json"),
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Object(mut o) => {
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let n = match o.pop(&~"variant") {
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Some(String(s)) => s,
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Some(val) => self.expected("string", &val),
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None => self.missing_field("variant", o)
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};
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match o.find(&~"fields").expect("invalidly encoded json") {
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&List(ref l) => {
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for field in l.rev_iter() {
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match o.pop(&~"fields") {
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Some(List(l)) => {
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for field in l.move_rev_iter() {
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self.stack.push(field.clone());
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}
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},
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_ => fail!("invalidly encoded json")
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Some(val) => self.expected("list", &val),
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None => {
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// re-insert the variant field so we're
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// printing the "whole" struct in the error
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// message... ick.
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o.insert(~"variant", String(n));
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self.missing_field("fields", o);
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}
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}
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n
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}
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ref json => fail!("invalid variant: {:?}", *json),
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json => self.expected("string or object", &json)
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};
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let idx = match names.iter().position(|n| str::eq_slice(*n, name)) {
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Some(idx) => idx,
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None => fail!("Unknown variant name: {}", name),
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None => self.err(format!("unknown variant name: {}", name))
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};
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f(self, idx)
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}
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@ -999,10 +1034,9 @@ impl serialize::Decoder for Decoder {
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-> T {
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debug!("read_struct_field(name={}, idx={})", name, idx);
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match self.stack.pop() {
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Object(obj) => {
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let mut obj = obj;
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Object(mut obj) => {
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let value = match obj.pop(&name.to_owned()) {
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None => fail!("no such field: {}", name),
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None => self.missing_field(name, obj),
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Some(json) => {
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self.stack.push(json);
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f(self)
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@ -1011,7 +1045,7 @@ impl serialize::Decoder for Decoder {
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self.stack.push(Object(obj));
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value
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}
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value => fail!("not an object: {:?}", value)
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value => self.expected("object", &value)
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}
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}
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@ -1058,7 +1092,7 @@ impl serialize::Decoder for Decoder {
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}
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len
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}
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_ => fail!("not a list"),
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value => self.expected("list", &value)
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};
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f(self, len)
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}
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@ -1079,7 +1113,7 @@ impl serialize::Decoder for Decoder {
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}
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len
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}
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json => fail!("not an object: {:?}", json),
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value => self.expected("object", &value)
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};
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f(self, len)
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}
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@ -1936,4 +1970,71 @@ mod tests {
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col: 8u,
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msg: @~"EOF while parsing object"}));
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}
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#[deriving(Decodable)]
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struct DecodeStruct {
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x: f64,
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y: bool,
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z: ~str,
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w: ~[DecodeStruct]
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}
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#[deriving(Decodable)]
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enum DecodeEnum {
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A(f64),
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B(~str)
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}
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fn check_err<T: Decodable<Decoder>>(to_parse: &'static str, expected_error: &str) {
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use std::task;
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let res = task::try(|| {
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// either fails in `decode` (which is what we want), or
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// returns Some(error_message)/None if the string was
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// invalid or valid JSON.
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match from_str(to_parse) {
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Err(e) => Some(e.to_str()),
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Ok(json) => {
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let _: T = Decodable::decode(&mut Decoder(json));
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None
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}
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}
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});
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match res {
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Ok(Some(parse_error)) => fail!("`{}` is not valid json: {}",
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to_parse, parse_error),
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Ok(None) => fail!("`{}` parsed & decoded ok, expecting error `{}`",
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to_parse, expected_error),
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Err(e) => {
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let err = e.as_ref::<~str>().unwrap();
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assert!(err.contains(expected_error),
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"`{}` errored incorrectly, found `{}` expecting `{}`",
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to_parse, *err, expected_error);
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}
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}
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}
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#[test]
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fn test_decode_errors_struct() {
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check_err::<DecodeStruct>("[]", "object but found list");
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check_err::<DecodeStruct>("{\"x\": true, \"y\": true, \"z\": \"\", \"w\": []}",
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"number but found boolean");
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check_err::<DecodeStruct>("{\"x\": 1, \"y\": [], \"z\": \"\", \"w\": []}",
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"boolean but found list");
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check_err::<DecodeStruct>("{\"x\": 1, \"y\": true, \"z\": {}, \"w\": []}",
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"string but found object");
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check_err::<DecodeStruct>("{\"x\": 1, \"y\": true, \"z\": \"\", \"w\": null}",
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"list but found null");
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check_err::<DecodeStruct>("{\"x\": 1, \"y\": true, \"z\": \"\"}",
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"'w' field in object");
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}
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#[test]
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fn test_decode_errors_enum() {
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check_err::<DecodeEnum>("{}",
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"'variant' field in object");
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check_err::<DecodeEnum>("{\"variant\": 1}",
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"string but found number");
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check_err::<DecodeEnum>("{\"variant\": \"A\"}",
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"'fields' field in object");
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check_err::<DecodeEnum>("{\"variant\": \"A\", \"fields\": null}",
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"list but found null");
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check_err::<DecodeEnum>("{\"variant\": \"C\", \"fields\": []}",
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"unknown variant name");
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}
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}
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