Fix newlines in JSON output (#4262)

* Fix newlines in JSON output

This changes the JSON output to be more consistent about where newlines are included. Previously it only included them between lines in a multiline diff. That meant single line changes were treated a bit weirdly. This changes it to append a newline to every line.

When feeding the results into `arc lint` this behaves correctly. I have only done limited testing though, in particular there's a possibility it might not work with files with `\r\n` endings (though that would have been the case before too).

Fixes #4259

* Update tests
# Conflicts:
#	tests/writemode/target/output.json

3 files changed, 22 insertions, 20 deletions

diff --git a/src/emitter/json.rs b/src/emitter/json.rs
index 7c0f862cbc6..c7f68d4675a 100644
--- a/src/emitter/json.rs
+++ b/src/emitter/json.rs
@@ -65,20 +65,22 @@ impl JsonEmitter {
             let mut expected_end_line = expected_begin_line;
             let mut original_line_counter = 0;
             let mut expected_line_counter = 0;
-            let mut original_lines = vec![];
-            let mut expected_lines = vec![];
+            let mut original = String::new();
+            let mut expected = String::new();
 
             for line in mismatch.lines {
                 match line {
                     DiffLine::Expected(msg) => {
                         expected_end_line = expected_begin_line + expected_line_counter;
                         expected_line_counter += 1;
-                        expected_lines.push(msg)
+                        expected.push_str(&msg);
+                        expected.push('\n');
                     }
                     DiffLine::Resulting(msg) => {
                         original_end_line = original_begin_line + original_line_counter;
                         original_line_counter += 1;
-                        original_lines.push(msg)
+                        original.push_str(&msg);
+                        original.push('\n');
                     }
                     DiffLine::Context(_) => continue,
                 }
@@ -89,8 +91,8 @@ impl JsonEmitter {
                 original_end_line,
                 expected_begin_line,
                 expected_end_line,
-                original: original_lines.join("\n"),
-                expected: expected_lines.join("\n"),
+                original,
+                expected,
             });
         }
         self.mismatched_files.push(MismatchedFile {
@@ -120,8 +122,8 @@ mod tests {
                 original_end_line: 79,
                 expected_begin_line: 79,
                 expected_end_line: 82,
-                original: String::from("fn Foo<T>() where T: Bar {"),
-                expected: String::from("fn Foo<T>()\nwhere\n    T: Bar,\n{"),
+                original: String::from("fn Foo<T>() where T: Bar {\n"),
+                expected: String::from("fn Foo<T>()\nwhere\n    T: Bar,\n{\n"),
             }],
         };
         let mismatch = Mismatch {
@@ -158,10 +160,10 @@ mod tests {
                 expected_begin_line: 5,
                 expected_end_line: 5,
                 original: String::from(
-                    "fn foo(_x: &u64) -> Option<&(dyn::std::error::Error + 'static)> {",
+                    "fn foo(_x: &u64) -> Option<&(dyn::std::error::Error + 'static)> {\n",
                 ),
                 expected: String::from(
-                    "fn foo(_x: &u64) -> Option<&(dyn ::std::error::Error + 'static)> {",
+                    "fn foo(_x: &u64) -> Option<&(dyn ::std::error::Error + 'static)> {\n",
                 ),
             }],
         };
@@ -260,8 +262,8 @@ mod tests {
                     original_end_line: 2,
                     expected_begin_line: 2,
                     expected_end_line: 2,
-                    original: String::from("println!(\"Hello, world!\");"),
-                    expected: String::from("    println!(\"Hello, world!\");"),
+                    original: String::from("println!(\"Hello, world!\");\n"),
+                    expected: String::from("    println!(\"Hello, world!\");\n"),
                 },
                 MismatchedBlock {
                     original_begin_line: 7,
@@ -269,10 +271,10 @@ mod tests {
                     expected_begin_line: 7,
                     expected_end_line: 10,
                     original: String::from(
-                        "#[test]\nfn it_works() {\n    assert_eq!(2 + 2, 4);\n}",
+                        "#[test]\nfn it_works() {\n    assert_eq!(2 + 2, 4);\n}\n",
                     ),
                     expected: String::from(
-                        "    #[test]\n    fn it_works() {\n        assert_eq!(2 + 2, 4);\n    }",
+                        "    #[test]\n    fn it_works() {\n        assert_eq!(2 + 2, 4);\n    }\n",
                     ),
                 },
             ],
@@ -321,8 +323,8 @@ mod tests {
                 original_end_line: 2,
                 expected_begin_line: 2,
                 expected_end_line: 2,
-                original: String::from("println!(\"Hello, world!\");"),
-                expected: String::from("    println!(\"Hello, world!\");"),
+                original: String::from("println!(\"Hello, world!\");\n"),
+                expected: String::from("    println!(\"Hello, world!\");\n"),
             }],
         };
 
@@ -333,8 +335,8 @@ mod tests {
                 original_end_line: 2,
                 expected_begin_line: 2,
                 expected_end_line: 2,
-                original: String::from("println!(\"Greetings!\");"),
-                expected: String::from("    println!(\"Greetings!\");"),
+                original: String::from("println!(\"Greetings!\");\n"),
+                expected: String::from("    println!(\"Greetings!\");\n"),
             }],
         };
 
diff --git a/tests/writemode/target/output.json b/tests/writemode/target/output.json
index acb33dea7ef..d8b5467ee91 100644
--- a/tests/writemode/target/output.json
+++ b/tests/writemode/target/output.json
@@ -1 +1 @@
-[{"name":"tests/writemode/source/json.rs","mismatches":[{"original_begin_line":5,"original_end_line":7,"expected_begin_line":5,"expected_end_line":5,"original":"fn foo_expr() {\n    1\n}","expected":"fn foo_expr() { 1 }"},{"original_begin_line":9,"original_end_line":11,"expected_begin_line":7,"expected_end_line":7,"original":"fn foo_stmt() {\n    foo();\n}","expected":"fn foo_stmt() { foo(); }"},{"original_begin_line":13,"original_end_line":15,"expected_begin_line":9,"expected_end_line":9,"original":"fn foo_decl_local()  {\n    let z = 5;\n   }","expected":"fn foo_decl_local() { let z = 5; }"},{"original_begin_line":17,"original_end_line":19,"expected_begin_line":11,"expected_end_line":11,"original":"fn    foo_decl_item(x: &mut i32) {\n    x = 3;\n}","expected":"fn foo_decl_item(x: &mut i32) { x = 3; }"},{"original_begin_line":21,"original_end_line":21,"expected_begin_line":13,"expected_end_line":13,"original":"   fn empty()     {","expected":"fn empty() {}"},{"original_begin_line":23,"original_end_line":23,"expected_begin_line":15,"expected_end_line":15,"original":"}","expected":"fn foo_return() -> String { \"yay\" }"},{"original_begin_line":25,"original_end_line":29,"expected_begin_line":17,"expected_end_line":20,"original":"fn foo_return() -> String {\n    \"yay\"\n}\n\nfn foo_where() -> T where T: Sync {","expected":"fn foo_where() -> T\nwhere\n    T: Sync,\n{"},{"original_begin_line":64,"original_end_line":66,"expected_begin_line":55,"expected_end_line":55,"original":"fn lots_of_space                      ()                                                           {\n                           1                 \n}","expected":"fn lots_of_space() { 1 }"},{"original_begin_line":71,"original_end_line":72,"expected_begin_line":60,"expected_end_line":60,"original":"    fn dummy(&self) {\n    }","expected":"    fn dummy(&self) {}"},{"original_begin_line":75,"original_end_line":75,"expected_begin_line":63,"expected_end_line":64,"original":"trait CoolerTypes { fn dummy(&self) { ","expected":"trait CoolerTypes {\n    fn dummy(&self) {}"},{"original_begin_line":77,"original_end_line":77,"expected_begin_line":66,"expected_end_line":66,"original":"}","expected":""},{"original_begin_line":79,"original_end_line":79,"expected_begin_line":67,"expected_end_line":70,"original":"fn Foo<T>() where T: Bar {","expected":"fn Foo<T>()\nwhere\n    T: Bar,\n{"}]}]
+[{"name":"tests/writemode/source/json.rs","mismatches":[{"original_begin_line":5,"original_end_line":7,"expected_begin_line":5,"expected_end_line":5,"original":"fn foo_expr() {\n    1\n}\n","expected":"fn foo_expr() { 1 }\n"},{"original_begin_line":9,"original_end_line":11,"expected_begin_line":7,"expected_end_line":7,"original":"fn foo_stmt() {\n    foo();\n}\n","expected":"fn foo_stmt() { foo(); }\n"},{"original_begin_line":13,"original_end_line":15,"expected_begin_line":9,"expected_end_line":9,"original":"fn foo_decl_local()  {\n    let z = 5;\n   }\n","expected":"fn foo_decl_local() { let z = 5; }\n"},{"original_begin_line":17,"original_end_line":19,"expected_begin_line":11,"expected_end_line":11,"original":"fn    foo_decl_item(x: &mut i32) {\n    x = 3;\n}\n","expected":"fn foo_decl_item(x: &mut i32) { x = 3; }\n"},{"original_begin_line":21,"original_end_line":21,"expected_begin_line":13,"expected_end_line":13,"original":"   fn empty()     {\n","expected":"fn empty() {}\n"},{"original_begin_line":23,"original_end_line":23,"expected_begin_line":15,"expected_end_line":15,"original":"}\n","expected":"fn foo_return() -> String { \"yay\" }\n"},{"original_begin_line":25,"original_end_line":29,"expected_begin_line":17,"expected_end_line":20,"original":"fn foo_return() -> String {\n    \"yay\"\n}\n\nfn foo_where() -> T where T: Sync {\n","expected":"fn foo_where() -> T\nwhere\n    T: Sync,\n{\n"},{"original_begin_line":64,"original_end_line":66,"expected_begin_line":55,"expected_end_line":55,"original":"fn lots_of_space                      ()                                                           {\n                           1                 \n}\n","expected":"fn lots_of_space() { 1 }\n"},{"original_begin_line":71,"original_end_line":72,"expected_begin_line":60,"expected_end_line":60,"original":"    fn dummy(&self) {\n    }\n","expected":"    fn dummy(&self) {}\n"},{"original_begin_line":75,"original_end_line":75,"expected_begin_line":63,"expected_end_line":64,"original":"trait CoolerTypes { fn dummy(&self) { \n","expected":"trait CoolerTypes {\n    fn dummy(&self) {}\n"},{"original_begin_line":77,"original_end_line":77,"expected_begin_line":66,"expected_end_line":66,"original":"}\n","expected":""},{"original_begin_line":79,"original_end_line":79,"expected_begin_line":67,"expected_end_line":70,"original":"fn Foo<T>() where T: Bar {\n","expected":"fn Foo<T>()\nwhere\n    T: Bar,\n{\n"}]}]
diff --git a/tests/writemode/target/stdin.json b/tests/writemode/target/stdin.json
index ae6796863e5..6f5d5bfb8ca 100644
--- a/tests/writemode/target/stdin.json
+++ b/tests/writemode/target/stdin.json
@@ -1 +1 @@
-[{"name":"stdin","mismatches":[{"original_begin_line":1,"original_end_line":6,"expected_begin_line":1,"expected_end_line":2,"original":"\nfn\n some( )\n{\n}\nfn main () {}","expected":"fn some() {}\nfn main() {}"}]}]
+[{"name":"stdin","mismatches":[{"original_begin_line":1,"original_end_line":6,"expected_begin_line":1,"expected_end_line":2,"original":"\nfn\n some( )\n{\n}\nfn main () {}\n","expected":"fn some() {}\nfn main() {}\n"}]}]