fix(OAS3): relative urls (#5341)

* Added tooling for appending OAS3 relative URLs to selected Server

Info
* Terms of service URL
* Contact URL
* License URL
* External Docs URL

Tag
* Tag External Docs URL

Operation
* Operation External Docs
** Operation Tag


Co-authored-by: Tim Lai <timothy.lai@gmail.com>

test/mocha/core/utils.js

@@ -32,6 +32,13 @@ import {
   generateCodeVerifier,
   createCodeChallenge,
 } from "core/utils"
+
+import { 
+  isAbsoluteUrl,
+  buildBaseUrl,
+  buildUrl,
+} from "core/utils/url"
+
 import win from "core/window"
 
 describe("utils", function() {
@@ -1334,6 +1341,92 @@ describe("utils", function() {
     })
   })
 
+  describe("isAbsoluteUrl", function() {
+
+    it("check if url is absolute", function() {
+      expect(!!isAbsoluteUrl("http://example.com")).toEqual(true)
+      expect(!!isAbsoluteUrl("https://secure-example.com")).toEqual(true)
+      expect(!!isAbsoluteUrl("HTTP://uppercase-example.com")).toEqual(true)
+      expect(!!isAbsoluteUrl("HTTP://uppercase-secure-example.com")).toEqual(true)
+      expect(!!isAbsoluteUrl("http://trailing-slash.com/")).toEqual(true)
+      expect(!!isAbsoluteUrl("ftp://file-transfer-protocol.com")).toEqual(true)
+      expect(!!isAbsoluteUrl("//no-protocol.com")).toEqual(true)
+    })
+
+    it("check if url is not absolute", function() {
+      expect(!!isAbsoluteUrl("/url-relative-to-host/base-path/path")).toEqual(false)
+      expect(!!isAbsoluteUrl("url-relative-to-base/base-path/path")).toEqual(false)      
+    })
+  })
+
+  describe("buildBaseUrl", function() {
+    const specUrl = "https://petstore.swagger.io/v2/swagger.json"
+    
+    const noServerSelected = ""
+    const absoluteServerUrl = "https://server-example.com/base-path/path"
+    const serverUrlRelativeToBase = "server-example/base-path/path"
+    const serverUrlRelativeToHost = "/server-example/base-path/path"
+
+    it("build base url with no server selected", function() {
+      expect(buildBaseUrl(noServerSelected, specUrl)).toBe("https://petstore.swagger.io/v2/swagger.json")
+    })
+
+    it("build base url from absolute server url", function() {
+      expect(buildBaseUrl(absoluteServerUrl, specUrl)).toBe("https://server-example.com/base-path/path")
+    })
+
+    it("build base url from relative server url", function() {
+      expect(buildBaseUrl(serverUrlRelativeToBase, specUrl)).toBe("https://petstore.swagger.io/v2/server-example/base-path/path")
+      expect(buildBaseUrl(serverUrlRelativeToHost, specUrl)).toBe("https://petstore.swagger.io/server-example/base-path/path")
+    })
+  })
+
+  describe("buildUrl", function() {
+    const specUrl = "https://petstore.swagger.io/v2/swagger.json"
+    
+    const noUrl = ""
+    const absoluteUrl = "https://example.com/base-path/path"
+    const urlRelativeToBase = "relative-url/base-path/path"
+    const urlRelativeToHost = "/relative-url/base-path/path"
+
+    const noServerSelected = ""
+    const absoluteServerUrl = "https://server-example.com/base-path/path"
+    const serverUrlRelativeToBase = "server-example/base-path/path"
+    const serverUrlRelativeToHost = "/server-example/base-path/path"
+    
+    it("build no url", function() {
+      expect(buildUrl(noUrl, specUrl, { selectedServer: absoluteServerUrl })).toBe(undefined)
+      expect(buildUrl(noUrl, specUrl, { selectedServer: serverUrlRelativeToBase })).toBe(undefined)
+      expect(buildUrl(noUrl, specUrl, { selectedServer: serverUrlRelativeToHost })).toBe(undefined)
+    })
+
+    it("build absolute url", function() {
+      expect(buildUrl(absoluteUrl, specUrl, { selectedServer: absoluteServerUrl })).toBe("https://example.com/base-path/path")
+      expect(buildUrl(absoluteUrl, specUrl, { selectedServer: serverUrlRelativeToBase })).toBe("https://example.com/base-path/path")
+      expect(buildUrl(absoluteUrl, specUrl, { selectedServer: serverUrlRelativeToHost })).toBe("https://example.com/base-path/path")
+    })
+
+    it("build relative url with no server selected", function() {
+      expect(buildUrl(urlRelativeToBase, specUrl, { selectedServer: noServerSelected })).toBe("https://petstore.swagger.io/v2/relative-url/base-path/path")
+      expect(buildUrl(urlRelativeToHost, specUrl, { selectedServer: noServerSelected })).toBe("https://petstore.swagger.io/relative-url/base-path/path")
+    })
+
+    it("build relative url with absolute server url", function() {
+      expect(buildUrl(urlRelativeToBase, specUrl, { selectedServer: absoluteServerUrl })).toBe("https://server-example.com/base-path/relative-url/base-path/path")
+      expect(buildUrl(urlRelativeToHost, specUrl, { selectedServer: absoluteServerUrl })).toBe("https://server-example.com/relative-url/base-path/path")
+    })
+
+    it("build relative url with server url relative to base", function() {
+      expect(buildUrl(urlRelativeToBase, specUrl, { selectedServer: serverUrlRelativeToBase })).toBe("https://petstore.swagger.io/v2/server-example/base-path/relative-url/base-path/path")
+      expect(buildUrl(urlRelativeToHost, specUrl, { selectedServer: serverUrlRelativeToBase })).toBe("https://petstore.swagger.io/relative-url/base-path/path")
+    })
+
+    it("build relative url with server url relative to host", function() {
+      expect(buildUrl(urlRelativeToBase, specUrl, { selectedServer: serverUrlRelativeToHost })).toBe("https://petstore.swagger.io/server-example/base-path/relative-url/base-path/path")
+      expect(buildUrl(urlRelativeToHost, specUrl, { selectedServer: serverUrlRelativeToHost })).toBe("https://petstore.swagger.io/relative-url/base-path/path")
+    })
+  })
+  
   describe("requiresValidationURL", function() {
     it("Should tell us if we require a ValidationURL", function() {
       const res = requiresValidationURL("https://example.com")