Merge pull request #12417 from quarto-dev/bugfix/12318

convert - ensure enough linebreaks between cells.

Author: cscheid

news/changelog-1.7.md

@@ -40,6 +40,7 @@ All changes included in 1.7:
 ## `quarto convert`
 
 - ([#12042](https://github.com/quarto-dev/quarto-cli/issues/12042)): Preserve Markdown content that follows YAML metadata in a `raw` .ipynb cell.
+- ([#12318](https://github.com/quarto-dev/quarto-cli/issues/12318)): Ensure enough line breaks between cells that might be trimmed.
 
 ## `quarto inspect`
 

src/command/convert/jupyter.ts

@@ -31,6 +31,7 @@ import {
   jupyterCellSrcAsStr,
 } from "../../core/jupyter/jupyter-shared.ts";
 import { assert } from "testing/asserts";
+import { getEndingNewlineCount } from "../../core/lib/text.ts";
 
 export async function markdownToJupyterNotebook(
   file: string,
@@ -80,9 +81,17 @@ export async function jupyterNotebookToMarkdown(
         cell,
       );
 
+      const endingNewLineCount = getEndingNewlineCount(md);
+      if (i > 0 && endingNewLineCount < 2) {
+        md.push("\n\n");
+      }
+
       // write markdown
       switch (cell.cell_type) {
         case "markdown":
+          // does the previous line have enough newlines?
+          // if not, add sufficient newlines so we have at least two
+          // between the last cell and this one
           md.push(...mdFromContentCell(cellWithOptions));
           break;
         case "raw":
@@ -123,6 +132,8 @@ export async function jupyterNotebookToMarkdown(
     }
   }
 
+  console.log({ md });
+
   // join into source
   const mdSource = md.join("");
 

src/core/lib/text.ts

@@ -315,3 +315,25 @@ export function normalizeCaseConvention(str: string): CaseConvention {
   }
   return result;
 }
+
+export const getEndingNewlineCount = (lines: string[]) => {
+  let count = 0;
+  for (let i = lines.length - 1; i >= 0; i--) {
+    if (lines[i].match(/^\n+$/)) { // only newlines
+      count += lines[i].length;
+      continue;
+    }
+    const m = lines[i].match(/\n+$/);
+    if (m) {
+      // newlines + other content
+      count += m[0].length;
+      break;
+    }
+    if (lines[i].length) {
+      // non-newline content
+      break;
+    }
+    // otherwise, continue
+  }
+  return count;
+};

tests/smoke/convert/issue-12318.test.ts

@@ -0,0 +1,42 @@
+/*
+* convert-backticks.test.ts
+*
+* Copyright (C) 2020-2024 Posit Software, PBC
+*
+*/
+
+import { existsSync } from "../../../src/deno_ral/fs.ts";
+import {
+  ExecuteOutput,
+  test,
+} from "../../test.ts";
+import { assert } from "testing/asserts";
+import { quarto } from "../../../src/quarto.ts";
+
+(() => {
+  const input = "docs/convert/issue-12318";
+  test({
+    // The name of the test
+    name: "issue-12318",
+  
+    // Sets up the test
+    context: {
+      teardown: async () => {
+        if (existsSync(input + '.ipynb')) {
+          Deno.removeSync(input + '.ipynb');
+        }
+      }
+    },
+  
+    // Executes the test
+    execute: async () => {
+      await quarto(["convert", "docs/convert/issue-12318.qmd"]);
+      await quarto(["convert", "docs/convert/issue-12318.ipynb", "--output", "issue-12318-2.qmd"]);
+      const txt = Deno.readTextFileSync("issue-12318-2.qmd");
+      assert(!txt.includes('}```'), "Triple backticks found not at beginning of line");
+    },
+  
+    verify: [],
+    type: "unit"
+  });
+})();

tests/unit/core/lib/text.test.ts

@@ -0,0 +1,66 @@
+/*
+ * core/lib/text.test.ts
+ *
+ * Copyright (C) 2025 Posit Software, PBC
+ */
+
+import { unitTest } from "../../../test.ts";
+import { assertEquals } from "testing/asserts";
+import { getEndingNewlineCount } from "../../../../src/core/lib/text.ts";
+
+unitTest("core/lib/text.ts - getEndingNewlineCount", async () => {
+  // Test case 1: No trailing newlines
+  assertEquals(getEndingNewlineCount(["content without newlines"]), 0);
+  assertEquals(getEndingNewlineCount(["line1", "line2", "line3"]), 0);
+
+  // Test case 2: Single line with trailing newlines
+  assertEquals(getEndingNewlineCount(["content\n"]), 1);
+  assertEquals(getEndingNewlineCount(["content\n\n\n"]), 3);
+
+  // Test case 3: Multiple lines with the last line having trailing newlines
+  assertEquals(getEndingNewlineCount(["line1", "line2", "line3\n\n"]), 2);
+  assertEquals(getEndingNewlineCount(["line1\n", "line2\n", "line3\n\n\n"]), 3);
+
+  // Test case 4: Empty lines at the end
+  assertEquals(getEndingNewlineCount(["content", "", ""]), 0);
+
+  // Test case 5: Lines with only newlines at the end
+  assertEquals(getEndingNewlineCount(["content", "\n", "\n\n"]), 3);
+  assertEquals(getEndingNewlineCount(["content", "\n\n\n"]), 3);
+
+  // Test case 6: Mixed scenario with empty lines and lines with only newlines
+  assertEquals(getEndingNewlineCount(["content\n", "", "\n\n", ""]), 3);
+  assertEquals(getEndingNewlineCount(["content", "", "\n", "\n\n", ""]), 3);
+
+  // Test case 7: Edge case with only empty strings
+  assertEquals(getEndingNewlineCount(["", "", ""]), 0);
+
+  // Test case 8: Edge case with an empty array
+  assertEquals(getEndingNewlineCount([]), 0);
+
+  // Test case 9: Content after newlines breaks the counting
+  assertEquals(getEndingNewlineCount(["line1\n\n", "line2"]), 0);
+  assertEquals(getEndingNewlineCount(["line1", "line2\n\n", "line3"]), 0);
+
+  // Test case 10: Complex scenario with mixed content
+  assertEquals(
+    getEndingNewlineCount([
+      "some content",
+      "more content\n",
+      "\n",
+      "",
+      "final line\n\n",
+    ]),
+    2,
+  );
+  assertEquals(
+    getEndingNewlineCount([
+      "line1",
+      "line2",
+      "line3\nwith content",
+      "\n",
+      "\n\n",
+    ]),
+    3,
+  );
+});