YAML: Apply trailingComma option (#9665)

changelog_unreleased/yaml/pr-9665.md

@@ -0,0 +1,46 @@
+#### Apply `trailingComma` option (#9665 by @fisker)
+
+When `--trailing-comma=none`, should not add trailing comma to flowMapping and flowSequence.
+
+<!-- prettier-ignore -->
+```yaml
+# Input
+flow-mapping:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+flow-sequence:
+  [
+    "object-does-not-fit-within-print-width", "------",
+    "TEST", "comma IS added here"
+  ]
+
+# Prettier stable
+mapping:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here",
+  }
+flow-sequence:
+  [
+    "object-does-not-fit-within-print-width",
+    "------",
+    "TEST",
+    "comma IS added here",
+  ]
+
+# Prettier master
+flow-mapping:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+flow-sequence:
+  [
+    "object-does-not-fit-within-print-width",
+    "------",
+    "TEST",
+    "comma IS added here"
+  ]
+```

src/language-yaml/printer-yaml.js

@@ -499,6 +499,8 @@ function _print(node, parentNode, path, options, print) {
           lastItem.type === "flowMappingItem" &&
           isEmptyNode(lastItem.key) &&
           isEmptyNode(lastItem.value))(getLast(node.children));
+      const trailingComma =
+        options.trailingComma === "none" ? "" : ifBreak(",", "");
       return concat([
         openMarker,
         indent(
@@ -526,7 +528,7 @@ function _print(node, parentNode, path, options, print) {
                 "children"
               )
             ),
-            ifBreak(",", ""),
+            trailingComma,
             hasEndComments(node)
               ? concat([
                   hardline,

tests/yaml/flow-mapping/trailing-comma/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,184 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`flow-mapping.yml - {"trailingComma":"all"} format 1`] = `
+====================================options=====================================
+parsers: ["yaml"]
+printWidth: 80
+trailingComma: "all"
+                                                                                | printWidth
+=====================================input======================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+
+expected:
+  {
+    "object-fits-within-print-width": "",
+    "TEST": "comma NOT here"
+  }
+
+---
+
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+=====================================output=====================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here",
+  }
+
+expected: { "object-fits-within-print-width": "", "TEST": "comma NOT here" }
+
+---
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+================================================================================
+`;
+
+exports[`flow-mapping.yml - {"trailingComma":"es5"} format 1`] = `
+====================================options=====================================
+parsers: ["yaml"]
+printWidth: 80
+trailingComma: "es5"
+                                                                                | printWidth
+=====================================input======================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+
+expected:
+  {
+    "object-fits-within-print-width": "",
+    "TEST": "comma NOT here"
+  }
+
+---
+
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+=====================================output=====================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here",
+  }
+
+expected: { "object-fits-within-print-width": "", "TEST": "comma NOT here" }
+
+---
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+================================================================================
+`;
+
+exports[`flow-mapping.yml - {"trailingComma":"none"} format 1`] = `
+====================================options=====================================
+parsers: ["yaml"]
+printWidth: 80
+trailingComma: "none"
+                                                                                | printWidth
+=====================================input======================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+
+expected:
+  {
+    "object-fits-within-print-width": "",
+    "TEST": "comma NOT here"
+  }
+
+---
+
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+=====================================output=====================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+
+expected: { "object-fits-within-print-width": "", "TEST": "comma NOT here" }
+
+---
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+================================================================================
+`;
+
+exports[`flow-mapping.yml format 1`] = `
+====================================options=====================================
+parsers: ["yaml"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+
+expected:
+  {
+    "object-fits-within-print-width": "",
+    "TEST": "comma NOT here"
+  }
+
+---
+
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+=====================================output=====================================
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here",
+  }
+
+expected: { "object-fits-within-print-width": "", "TEST": "comma NOT here" }
+
+---
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }
+
+================================================================================
+`;

tests/yaml/flow-mapping/trailing-comma/flow-mapping.yml

@@ -0,0 +1,19 @@
+failing:
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma IS added here"
+  }
+
+expected:
+  {
+    "object-fits-within-print-width": "",
+    "TEST": "comma NOT here"
+  }
+
+---
+
+does not suffice: >
+  {
+    "object-does-not-fit-within-print-width": "------",
+    "TEST": "comma NOT here — but object's now a string due to '>'"
+  }

tests/yaml/flow-mapping/trailing-comma/jsfmt.spec.js

@@ -0,0 +1,4 @@
+run_spec(__dirname, ["yaml"]);
+run_spec(__dirname, ["yaml"], { trailingComma: "none" });
+run_spec(__dirname, ["yaml"], { trailingComma: "es5" });
+run_spec(__dirname, ["yaml"], { trailingComma: "all" });