Improve path validation of templated created pages

[BenSurgisonGDS]

See: You can create a page from a template with no name

Added validation and acceptance tests for:

• Path already exists
• Path not entered
• Path only containing spaces
• Path with only a single slash
• Path missing a starting slash
• Path ending in a slash
• Path containing consecutive slashes
• Path containing a search parameter
• Path containing spaces
• Path including invalid characters

[joelanman]

don't have time for a full review until later, but one point - I think we talk about a 'path' on the page, and have 'URL' in the errors - we should use 'path' throughout

[joelanman]

having problems checking this out to test - I've tried

• git clean -dfx
• npm install
• npm run start:package

and I get

GOV.UK Prototype Kit 13.0.1

starting...
node:internal/modules/cjs/loader:936
  throw err;
  ^

Error: Cannot find module 'govuk-prototype-kit'
Require stack:
- /Users/joelanman/projects/govuk-prototype-kit/cypress/fixtures/extensions/extension-bar/filters.js
- /Users/joelanman/projects/govuk-prototype-kit/lib/utils.js
- /Users/joelanman/projects/govuk-prototype-kit/lib/middleware/authentication/authentication.js
- /Users/joelanman/projects/govuk-prototype-kit/server.js
- /Users/joelanman/projects/govuk-prototype-kit/listen-on-port.js
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
    at Function.Module._load (node:internal/modules/cjs/loader:778:27)
    at Module.require (node:internal/modules/cjs/loader:1005:19)
    at require (node:internal/modules/cjs/helpers:102:18)
    at Object.<anonymous> (/Users/joelanman/projects/govuk-prototype-kit/cypress/fixtures/extensions/extension-bar/filters.js:1:23)
    at Module._compile (node:internal/modules/cjs/loader:1101:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:822:12)
    at Module.require (node:internal/modules/cjs/loader:1005:19) {
  code: 'MODULE_NOT_FOUND',

[joelanman]

just wondering if we should use path throughout, unless we are sometimes dealing with urls?

[BenSurgisonGDS]

The headings on the page were not part of the PR. The only reason they are referenced is to for the acceptance tests. Should this be in another PR?

[joelanman]

it should not allow paths with multiple consecutive slashes

[joelanman]

Looks good, just needs a changelog