Remove initial empty cell from codeManager.getCells() (#1505)

* Remove initial empty cell from getCells()

* Include any initial whitespace on line with first text

* Fix tests

* Add tests for code-manager.getCells

* Fix tests; append cells to an empty notebook

lib/code-manager.js

@@ -282,18 +282,26 @@ export function getCells(
   } else {
     breakpoints = getBreakpoints(editor);
   }
-  return getCellsForBreakPoints(breakpoints);
+  return getCellsForBreakPoints(editor, breakpoints);
 }
 
 export function getCellsForBreakPoints(
+  editor: atom$TextEditor,
   breakpoints: Array<atom$Point>
 ): Array<atom$Range> {
   let start = new Point(0, 0);
-  return _.map(breakpoints, end => {
-    const cell = new Range(start, end);
-    start = new Point(end.row + 1, 0);
-    return cell;
+  // Let start be earliest row with text
+  editor.scan(/\S/, match => {
+    start = new Point(match.range.start.row, 0);
+    match.stop();
   });
+  return _.compact(
+    _.map(breakpoints, end => {
+      const cell = end.isEqual(start) ? null : new Range(start, end);
+      start = new Point(end.row + 1, 0);
+      return cell;
+    })
+  );
 }
 
 export function moveDown(editor: atom$TextEditor, row: number) {

spec/code-manager-spec.js

@@ -69,7 +69,9 @@ describe("CodeManager", () => {
           [[6, 0], [10, 5]]
         ].map(toRange); // zero-to-bp1 // nextRow of bp1 to bp2 // nextRow of bp2 to bp3 // nextRow of bp3 to bp4
 
-        expect(CM.getCellsForBreakPoints(points)).toEqual(cellsExpected);
+        expect(CM.getCellsForBreakPoints(editor, points)).toEqual(
+          cellsExpected
+        );
       });
     });
     describe("getCells", () => {
@@ -101,6 +103,42 @@ describe("CodeManager", () => {
           ].map(toRange); // zero-to-row0:bp // nextRow of row0:bp to row2:bp // nextRow of row2:bp to EOF(= implicit bp)
           expect(CM.getCells(editor)).toEqual(cellsExpected);
         });
+        it("doesn't create cell from initial empty whitespace", () => {
+          const code = [
+            "",
+            "",
+            "print('hello world')",
+            "# %%",
+            "print('foo bar')"
+          ];
+          editor.setText(code.join("\n") + "\n");
+          const cellsExpected = [[[2, 0], [3, 0]], [[4, 0], [5, 0]]].map(
+            toRange
+          );
+          expect(CM.getCells(editor)).toEqual(cellsExpected);
+        });
+        it("doesn't create cell from initial empty whitespace with cell marker", () => {
+          const code = [
+            "",
+            "# %%",
+            "print('hello world')",
+            "# %%",
+            "print('foo bar')"
+          ];
+          editor.setText(code.join("\n") + "\n");
+          const cellsExpected = [[[2, 0], [3, 0]], [[4, 0], [5, 0]]].map(
+            toRange
+          );
+          expect(CM.getCells(editor)).toEqual(cellsExpected);
+        });
+        it("doesn't create initial empty cell with no whitespace", () => {
+          const code = ["print('hello world')", "# %%", "print('foo bar')"];
+          editor.setText(code.join("\n") + "\n");
+          const cellsExpected = [[[0, 0], [1, 0]], [[2, 0], [3, 0]]].map(
+            toRange
+          );
+          expect(CM.getCells(editor)).toEqual(cellsExpected);
+        });
       });
       describe("with arg(= breakpoints)", () => {
         it("return cells(range) from passed breakpoints(with auto-sort-by-position)", () => {

spec/store/index-spec.js

@@ -315,14 +315,10 @@ describe("Store", () => {
       expect(store.notebook).toBeNull();
     });
 
-    it("should return a single cell notebook for empty file", () => {
+    it("should return an empty notebook for empty file", () => {
       store.updateEditor(editor);
       // Build a notebook with one code cell.
-      let codeCell = commutable.emptyCodeCell.set("source", "");
-      const nb = commutable.appendCellToNotebook(
-        commutable.emptyNotebook,
-        codeCell
-      );
+      const nb = commutable.emptyNotebook;
       expect(store.notebook).toEqual(commutable.toJS(nb));
     });
 
@@ -336,7 +332,7 @@ describe("Store", () => {
       // The outputted notebook will have three cells because currently a cell
       // is always created before the first `# %%`
       let nb = commutable.appendCellToNotebook(
-        commutable.monocellNotebook,
+        commutable.emptyNotebook,
         codeCell1
       );
       nb = commutable.appendCellToNotebook(nb, codeCell2);
@@ -353,7 +349,7 @@ describe("Store", () => {
       // The outputted notebook will have three cells because currently a cell
       // is always created before the first `# %%`
       let nb = commutable.appendCellToNotebook(
-        commutable.monocellNotebook,
+        commutable.emptyNotebook,
         codeCell
       );
       nb = commutable.appendCellToNotebook(nb, markdownCell);