We avoid prepending a hardline before a LabelDefinition (#456)

Author: Janther

src/nodes/print-preserving-empty-lines.js

@@ -11,7 +11,13 @@ function printPreservingEmptyLines(path, key, options, print) {
     const node = childPath.getValue();
     const nodeType = node.type;
 
-    if (parts.length !== 0) {
+    if (
+      // Avoid adding a hardline at the beggining of the document.
+      parts.length !== 0 &&
+      // LabelDefinition adds a dedented line so we have to avoid prepending
+      // a hardline.
+      nodeType !== 'LabelDefinition'
+    ) {
       parts.push(hardline);
     }
 

tests/Assembly/Assembly.sol

@@ -117,6 +117,7 @@ loop:
     a add swap1
     n := sub(n, 1)
     jump(loop)
+
 loopend:
     mstore(0, a)
     return(0, 0x20)

tests/Assembly/__snapshots__/jsfmt.spec.js.snap

@@ -125,6 +125,7 @@ loop:
     a add swap1
     n := sub(n, 1)
     jump(loop)
+
 loopend:
     mstore(0, a)
     return(0, 0x20)
@@ -322,7 +323,6 @@ contract Assembly {
             let n := calldataload(4)
             let a := 1
             let b := a
-
         loop:
             jumpi(loopend, eq(n, 0))
             a
@@ -339,19 +339,16 @@ contract Assembly {
         assembly {
             let x := 8
             jump(two)
-
         one:
             // Here the stack height is 2 (because we pushed x and 7),
             // but the assembler thinks it is 1 because it reads
             // from top to bottom.
             // Accessing the stack variable x here will lead to errors.
             x := 9
             jump(three)
-
         two:
             7 // push something onto the stack
             jump(one)
-
         three:
         }
     }

tests_config/run_spec.js

@@ -18,17 +18,25 @@ const CURSOR_PLACEHOLDER = '<|>';
 const RANGE_START_PLACEHOLDER = '<<<PRETTIER_RANGE_START>>>';
 const RANGE_END_PLACEHOLDER = '<<<PRETTIER_RANGE_END>>>';
 
-// TODO: these test files need fix
+// Here we add files that will not be the same when formating a second time.
 const unstableTests = new Map(
-  ['Assembly/Assembly.sol'].map((fixture) => {
+  [].map((fixture) => {
     const [file, isUnstable = () => true] = Array.isArray(fixture)
       ? fixture
       : [fixture];
     return [path.join(__dirname, '../tests/', file), isUnstable];
   })
 );
 
-const unstableAstTests = new Map();
+// Here we add files that will not have the same AST after being formated.
+const unstableAstTests = new Map(
+  [].map((fixture) => {
+    const [file, isAstUnstable = () => true] = Array.isArray(fixture)
+      ? fixture
+      : [fixture];
+    return [path.join(__dirname, '../tests/', file), isAstUnstable];
+  })
+);
 
 const isUnstable = (filename, options) => {
   const testFunction = unstableTests.get(filename);