refactor: Add ExcludeSubItemsField, for handling 'exclude sub-items' filter (#817)

* test: Add Query-based tests for 'exclude sub-items'

* feat: Add ExcludeSubItemsField class - for 'exclude sub-items'

* refactor: Re-implement 'exclude sub-items' in Query using ExcludeSubItemsField

* test: Clean up tests for ExcludeSubItemsField

* test: Make ExcludeSubItemsField.test.ts more readable and thorough

* chore: Add jsdoc for ExcludeSubItemsField

Author: claremacrae

src/Query.ts

@@ -10,6 +10,7 @@ import type { Field } from './Query/Filter/Field';
 import { DescriptionField } from './Query/Filter/DescriptionField';
 import { DoneDateField } from './Query/Filter/DoneDateField';
 import { DueDateField } from './Query/Filter/DueDateField';
+import { ExcludeSubItemsField } from './Query/Filter/ExcludeSubItemsField';
 import { HeadingField } from './Query/Filter/HeadingField';
 import { PathField } from './Query/Filter/PathField';
 import { PriorityField } from './Query/Filter/PriorityField';
@@ -73,7 +74,6 @@ export class Query implements IQuery {
     private readonly shortModeRegexp = /^short/;
 
     private readonly limitRegexp = /^limit (to )?(\d+)( tasks?)?/;
-    private readonly excludeSubItemsString = 'exclude sub-items';
 
     private readonly commentRegexp = /^#.*/;
 
@@ -86,9 +86,6 @@ export class Query implements IQuery {
                 switch (true) {
                     case line === '':
                         break;
-                    case line === this.excludeSubItemsString:
-                        this._filters.push((task) => task.indentation === '');
-                        break;
                     case this.shortModeRegexp.test(line):
                         this._layoutOptions.shortMode = true;
                         break;
@@ -116,6 +113,8 @@ export class Query implements IQuery {
                         break;
                     case this.parseFilter(line, new HeadingField()):
                         break;
+                    case this.parseFilter(line, new ExcludeSubItemsField()):
+                        break;
                     case this.limitRegexp.test(line):
                         this.parseLimit({ line });
                         break;

src/Query/Filter/ExcludeSubItemsField.ts

@@ -0,0 +1,35 @@
+import { Field } from './Field';
+import type { FilterOrErrorMessage } from './Filter';
+import { FilterInstructions } from './FilterInstructions';
+
+/**
+ * Implements 'exclude sub-items' filter
+ */
+export class ExcludeSubItemsField extends Field {
+    private readonly _filters = new FilterInstructions();
+
+    constructor() {
+        super();
+
+        this._filters.add(
+            'exclude sub-items',
+            (task) => task.indentation === '',
+        );
+    }
+
+    public canCreateFilterForLine(line: string): boolean {
+        return this._filters.canCreateFilterForLine(line);
+    }
+
+    public createFilterOrErrorMessage(line: string): FilterOrErrorMessage {
+        return this._filters.createFilterOrErrorMessage(line);
+    }
+
+    protected fieldName(): string {
+        return 'exclude';
+    }
+
+    protected filterRegexp(): RegExp | null {
+        return null;
+    }
+}

tests/Query/Filter/ExcludeSubItemsField.test.ts

@@ -0,0 +1,19 @@
+// 'exclude sub-items'
+
+import { testTaskFilter } from '../../TestingTools/FilterTestHelpers';
+import { fromLine } from '../../TestHelpers';
+import { ExcludeSubItemsField } from '../../../src/Query/Filter/ExcludeSubItemsField';
+
+describe('sub-items', () => {
+    it('exclude sub-items', () => {
+        // Arrange
+        const filter = new ExcludeSubItemsField().createFilterOrErrorMessage(
+            'exclude sub-items',
+        );
+
+        // Assert
+        testTaskFilter(filter, fromLine({ line: '- [ ] Task' }), true);
+        testTaskFilter(filter, fromLine({ line: '  - [ ] Subtask1' }), false);
+        testTaskFilter(filter, fromLine({ line: '    - [ ] Subtask2' }), false);
+    });
+});