fix: Fix searching for unescaped paths via regex

This fixes #1037.

It turned out that when creating RegExp objects from strings,
TypeScript automatically escapes un-escaped forward slashes (/).

But the previous validation code in validateAndConstruct() was wrongly
truncating queries at the first unescaped forward slash.

By removing that validation, it is now possible to use unescaped paths
in regular expressions (providing that they don't have any other
unescaped special characters, of course).

And if the regular expression does have an error, the user will now get
a meaningful error message via the exception thrown by the RegExp
constructor.

Previous searches where '/' characters are escaped will still work,
but this escaping is no longer necessary.

src/Query/Matchers/RegexMatcher.ts

@@ -27,8 +27,7 @@ export class RegexMatcher extends IStringMatcher {
      * @throws {SyntaxError} Throws an exception if there was an error in {@link regexInput}.
      */
     public static validateAndConstruct(regexInput: string): RegexMatcher | null {
-        // Courtesy of https://stackoverflow.com/questions/17843691/javascript-regex-to-match-a-regex
-        const regexPattern = /\/((?![*+?])(?:[^\r\n[/\\]|\\.|\[(?:[^\r\n\]\\]|\\.)*])+)\/([igmu]*)/;
+        const regexPattern = /^\/(.+)\/([igmu]*)/;
         const query = regexInput.match(regexPattern);
 
         if (query !== null) {

tests/Query/Filter/PathField.test.ts

@@ -76,33 +76,18 @@ describe('path', () => {
     });
 });
 
-describe('invalid unescaped slash should give helpful error text and not search', () => {
+describe('should use whole path with un-escaped slashes in query', () => {
     const filterWithUnescapedSlashes = new PathField().createFilterOrErrorMessage(
         String.raw`path regex matches /a/b/c/d/`,
     );
 
-    // This test demonstrates the issue logged in
-    // https://github.com/obsidian-tasks-group/obsidian-tasks/issues/1037
-    //      'Work out how to prevent `path regex matches /a/b/c/d/` from
-    //       confusingly only searching `path regex matches /a/`.
-    // All these tests are marked as 'failing' because the code currently accepts
-    // an invalid search.
-    it.failing('should not be valid', () => {
-        expect(filterWithUnescapedSlashes).not.toBeValid();
+    it('should escape backslashes in query automatically', () => {
+        expect(filterWithUnescapedSlashes).toBeValid();
+        expect(filterWithUnescapedSlashes).toHaveExplanation("using regex:     'a\\/b\\/c\\/d' with no flags");
     });
 
-    it.failing('should have a meaningful error message', () => {
-        // The error message does not have to be exactly this.
-        // The main thing is that it should convey what the user needs to do
-        // to fix the expression.
-        expect(filterWithUnescapedSlashes.error).toEqual(
-            'An unescaped delimiter must be escaped; in most languages with a backslash (\\)',
-        );
-    });
-
-    it.failing('should not match a subset of requested path', () => {
-        // Once the issue is fixed, and filterWithUnescapedSlashes is not valid,
-        // this test should be deleted.
+    it('should match the requested path', () => {
+        expect(filterWithUnescapedSlashes).toMatchTaskWithPath('/a/b/c/d/e.md');
         expect(filterWithUnescapedSlashes).not.toMatchTaskWithPath('/a/b.md');
     });
 });

tests/Query/Filter/TextField.test.explains_regular_expression_searches_bulk_test.approved.txt

@@ -8,7 +8,7 @@ description regex matches /  / =>
   using regex:            '  ' with no flags
 
 description regex matches /#context/pc_photos|#context/pc_clare|#context/pc_macbook/i =>
-  using regex:            '#context' with no flags
+  using regex:            '#context\/pc_photos|#context\/pc_clare|#context\/pc_macbook' with flag 'i'
 
 description regex matches /#context\/pc_photos|#context\/pc_clare|#context\/pc_macbook/i =>
   using regex:            '#context\/pc_photos|#context\/pc_clare|#context\/pc_macbook' with flag 'i'
@@ -41,7 +41,7 @@ filename regex does not match /^Tasks User Support Kanban\.md$/ =>
   using regex:                '^Tasks User Support Kanban\.md$' with no flags
 
 folder regex matches /root/sub-folder/sub-sub-folder/ =>
-  using regex:       'root' with no flags
+  using regex:       'root\/sub-folder\/sub-sub-folder' with no flags
 
 folder regex matches /root\/sub-folder\/sub-sub-folder/ =>
   using regex:       'root\/sub-folder\/sub-sub-folder' with no flags
@@ -77,7 +77,7 @@ path regex matches /clare/i =>
   using regex:     'clare' with flag 'i'
 
 path regex matches /root/sub-folder/sub-sub-folder/index\.md/ =>
-  using regex:     'root' with no flags
+  using regex:     'root\/sub-folder\/sub-sub-folder\/index\.md' with no flags
 
 path regex matches /root\/sub-folder\/sub-sub-folder\/index\.md/ =>
   using regex:     'root\/sub-folder\/sub-sub-folder\/index\.md' with no flags

tests/Query/Matchers/RegexMatcher.test.ts

@@ -24,12 +24,12 @@ describe('RegexMatcher', () => {
 });
 
 describe('RegexMatcher source', () => {
-    it.failing('should allow multiple slashes in source', () => {
+    it('should allow multiple slashes in source', () => {
         const matcher = RegexMatcher.validateAndConstruct('/a/b/c/d/');
         expect(matcher!.regex.source).toEqual(String.raw`a\/b\/c\/d`);
     });
 
-    it.failing('should allow multiple slashes and delimiters in source', () => {
+    it('should allow multiple slashes and delimiters in source', () => {
         const matcher = RegexMatcher.validateAndConstruct('//a/b/c/d//');
         expect(matcher!.regex.source).toEqual(String.raw`\/a\/b\/c\/d\/`);
     });