Markdown and MDX configuration rework (#5684)

* feat: change extendDefaults -> gfm

* deps: remove smartypants from md/remark

* tests: update markdown plugin tests

* fix: borked lockfile

* feat: allow all Markdown options in MDX config, with extend

* deps: remove smartypants from MDX

* chore: remove unused `mode` property

* chore: remark rehype types

* chore: dead code

* fix: order of default config properties

* refactor: move md defaults to remark

* fix: RemarkRehype type

* fix: apply defaults based on MD defaults

* chore: update plugin tests

* chore: add syntaxHighlight test

* refactor: remove drafts from config defaults

* docs: new MDX config options

* chore: add changeset

* edit: test both extends for syntax highlight

* refactor: remove MDX config deep merge

* docs: update README and changeset

* edit: avoid -> disable

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

* edit: `drafts` clarification

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

* edit: remove "scare quotes"

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

* docs: MDX config options redraft

* docs: add migration

* chore: changeset heading levels

* refactor: githubFlavoredMarkdown -> gfm

* chore: remove unused imports

Co-authored-by: Sarah Rainsberger <sarah@rainsberger.ca>

1 files changed, 50 insertions, 84 deletions

diff --git a/packages/integrations/mdx/test/mdx-plugins.test.js b/packages/integrations/mdx/test/mdx-plugins.test.js
index a077fde45..f74ded3ea 100644
--- a/packages/integrations/mdx/test/mdx-plugins.test.js
+++ b/packages/integrations/mdx/test/mdx-plugins.test.js
@@ -80,91 +80,57 @@ describe('MDX plugins', () => {
 		expect(selectTocLink(document)).to.be.null;
 	});
 
-	it('respects "extendDefaultPlugins" when extending markdown', async () => {
-		const fixture = await buildFixture({
-			markdown: {
-				remarkPlugins: [remarkExamplePlugin],
-				rehypePlugins: [rehypeExamplePlugin],
-				extendDefaultPlugins: true,
-			},
-			integrations: [mdx()],
-		});
-
-		const html = await fixture.readFile(FILE);
-		const { document } = parseHTML(html);
-
-		expect(selectRemarkExample(document)).to.not.be.null;
-		expect(selectRehypeExample(document)).to.not.be.null;
-		expect(selectGfmLink(document)).to.not.be.null;
-	});
-
-	it('extends markdown config with extendPlugins: "markdown"', async () => {
-		const fixture = await buildFixture({
-			markdown: {
-				remarkPlugins: [remarkExamplePlugin],
-				rehypePlugins: [rehypeExamplePlugin],
-			},
-			integrations: [
-				mdx({
-					extendPlugins: 'markdown',
-					remarkPlugins: [remarkToc],
-				}),
-			],
-		});
-
-		const html = await fixture.readFile(FILE);
-		const { document } = parseHTML(html);
-
-		expect(selectRemarkExample(document)).to.not.be.null;
-		expect(selectRehypeExample(document)).to.not.be.null;
-		expect(selectTocLink(document)).to.not.be.null;
-	});
-
-	it('extends default plugins with extendPlugins: "astroDefaults"', async () => {
-		const fixture = await buildFixture({
-			markdown: {
-				// should NOT be applied to MDX
-				remarkPlugins: [remarkToc],
-			},
-			integrations: [
-				mdx({
-					remarkPlugins: [remarkExamplePlugin],
-					rehypePlugins: [rehypeExamplePlugin],
-					extendPlugins: 'astroDefaults',
-				}),
-			],
-		});
-
-		const html = await fixture.readFile(FILE);
-		const { document } = parseHTML(html);
-
-		expect(selectGfmLink(document)).to.not.be.null;
-		// remark and rehype plugins still respected
-		expect(selectRemarkExample(document)).to.not.be.null;
-		expect(selectRehypeExample(document)).to.not.be.null;
-		// Does NOT inherit TOC from markdown config
-		expect(selectTocLink(document)).to.be.null;
-	});
-
-	it('does not extend default plugins with extendPlugins: false', async () => {
-		const fixture = await buildFixture({
-			markdown: {
-				remarkPlugins: [remarkExamplePlugin],
-			},
-			integrations: [
-				mdx({
-					remarkPlugins: [],
-					extendPlugins: false,
-				}),
-			],
+	for (const extendMarkdownConfig of [true, false]) {
+		describe(`extendMarkdownConfig = ${extendMarkdownConfig}`, () => {
+			let fixture;
+			before(async () => {
+				fixture = await buildFixture({
+					markdown: {
+						remarkPlugins: [remarkToc],
+						gfm: false,
+					},
+					integrations: [
+						mdx({
+							extendMarkdownConfig,
+							remarkPlugins: [remarkExamplePlugin],
+							rehypePlugins: [rehypeExamplePlugin],
+						}),
+					],
+				});
+			});
+
+			it('Handles MDX plugins', async () => {
+				const html = await fixture.readFile(FILE);
+				const { document } = parseHTML(html);
+
+				expect(selectRemarkExample(document, 'MDX remark plugins not applied.')).to.not.be.null;
+				expect(selectRehypeExample(document, 'MDX rehype plugins not applied.')).to.not.be.null;
+			});
+
+			it('Handles Markdown plugins', async () => {
+				const html = await fixture.readFile(FILE);
+				const { document } = parseHTML(html);
+
+				expect(
+					selectTocLink(
+						document,
+						'`remarkToc` plugin applied unexpectedly. Should override Markdown config.'
+					)
+				).to.be.null;
+			});
+
+			it('Handles gfm', async () => {
+				const html = await fixture.readFile(FILE);
+				const { document } = parseHTML(html);
+
+				if (extendMarkdownConfig === true) {
+					expect(selectGfmLink(document), 'Does not respect `markdown.gfm` option.').to.be.null;
+				} else {
+					expect(selectGfmLink(document), 'Respects `markdown.gfm` unexpectedly.').to.not.be.null;
+				}
+			});
 		});
-
-		const html = await fixture.readFile(FILE);
-		const { document } = parseHTML(html);
-
-		expect(selectGfmLink(document)).to.be.null;
-		expect(selectRemarkExample(document)).to.be.null;
-	});
+	}
 
 	it('supports custom recma plugins', async () => {
 		const fixture = await buildFixture({