feat(markdown): auto-detect which number style of ordered list to be used (#3029)

src/printer-markdown.js

@@ -175,10 +175,23 @@ function genericPrint(path, options, print) {
         node,
         path.getParentNode()
       );
+
+      const isGitDiffFriendlyOrderedList =
+        node.ordered &&
+        node.children.length > 1 &&
+        /^\s*1(\.|\))/.test(
+          options.originalText.slice(
+            node.children[1].position.start.offset,
+            node.children[1].position.end.offset
+          )
+        );
+
       return printChildren(path, options, print, {
         processor: (childPath, index) => {
           const prefix = node.ordered
-            ? (index === 0 ? node.start : 1) +
+            ? (index === 0
+                ? node.start
+                : isGitDiffFriendlyOrderedList ? 1 : node.start + index) +
               (nthSiblingIndex % 2 === 0 ? ". " : ") ")
             : nthSiblingIndex % 2 === 0 ? "* " : "- ";
           return concat([prefix, align(prefix.length, childPath.call(print))]);

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

@@ -2243,7 +2243,7 @@ This is a paragraph.
 > ## This is a header.
 >
 > 1. This is the first list item.
-> 1. This is the second list item.
+> 2. This is the second list item.
 >
 > Here's some example code:
 >

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

@@ -11,6 +11,17 @@ exports[`checkbox.md 1`] = `
 
 `;
 
+exports[`git-diff-friendly.md 1`] = `
+5. abc
+1. def
+999. ghi
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+5. abc
+1. def
+1. ghi
+
+`;
+
 exports[`long-paragraph.md 1`] = `
 - This is a long long long long long long long long long long long long long long paragraph.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -113,7 +124,7 @@ exports[`start.md 1`] = `
 7. ghi
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 5. abc
-1. def
-1. ghi
+6. def
+7. ghi
 
 `;

tests/markdown_list/git-diff-friendly.md

@@ -0,0 +1,3 @@
+5. abc
+1. def
+999. ghi

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

@@ -2765,8 +2765,8 @@ exports[`example-243.md 1`] = `
 3. bar
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1. foo
-1.
-1. bar
+2.
+3. bar
 
 `;
 
@@ -2967,7 +2967,7 @@ exports[`example-261.md 1`] = `
 3) baz
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 1. foo
-1. bar
+2. bar
 
 3) baz