fix(HTML, Vue): don't break the template element included in a line shorter than print-width (#6284)

CHANGELOG.unreleased.md

@@ -315,6 +315,30 @@ This version updates the TypeScript parser to correctly handle JSX text with dou
 
 Flag used with `--write` to avoid re-checking files that were not changed since they were last written (with the same formatting configuration).
 
+#### HTML, Vue: Don't break the template element included in a line shorter than print-width([#6284] by [@sosukesuzuki])
+
+Previously, even if the line length is shorter than print-width is Prettier breaks the line with a template element.
+
+<!-- prettier-ignore -->
+```html
+// Input
+<template>
+  <template>foo</template>
+</template>
+
+// Output (Prettier stable)
+<template>
+  <template
+    >foo</template
+  >
+</template>
+
+// Output (Prettier master)
+<template>
+  <template>foo</template>
+</template>
+```
+
 [#5910]: https://github.com/prettier/prettier/pull/5910
 [#6186]: https://github.com/prettier/prettier/pull/6186
 [#6206]: https://github.com/prettier/prettier/pull/6206
@@ -325,6 +349,7 @@ Flag used with `--write` to avoid re-checking files that were not changed since
 [#6270]: https://github.com/prettier/prettier/pull/6270
 [#6289]: https://github.com/prettier/prettier/pull/6289
 [#6332]: https://github.com/prettier/prettier/pull/6332
+[#6284]: https://github.com/prettier/prettier/pull/6284
 [@duailibe]: https://github.com/duailibe
 [@gavinjoyce]: https://github.com/gavinjoyce
 [@sosukesuzuki]: https://github.com/sosukesuzuki

src/language-html/utils.js

@@ -272,7 +272,7 @@ function forceBreakContent(node) {
     forceBreakChildren(node) ||
     (node.type === "element" &&
       node.children.length !== 0 &&
-      (["body", "template", "script", "style"].indexOf(node.name) !== -1 ||
+      (["body", "script", "style"].indexOf(node.name) !== -1 ||
         node.children.some(child => hasNonTextChild(child)))) ||
     (node.firstChild &&
       node.firstChild === node.lastChild &&

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

@@ -332,3 +332,31 @@ printWidth: 80
 
 ================================================================================
 `;
+
+exports[`template.html 1`] = `
+====================================options=====================================
+parsers: ["html"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<template>
+  <template>foo</template>
+</template>
+
+<template>
+  <template>foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo</template>
+</template>
+
+=====================================output=====================================
+<template>
+  <template>foo</template>
+</template>
+
+<template>
+  <template
+    >foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo</template
+  >
+</template>
+
+================================================================================
+`;

tests/html_whitespace/template.html

@@ -0,0 +1,7 @@
+<template>
+  <template>foo</template>
+</template>
+
+<template>
+  <template>foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo</template>
+</template>