UrlUtils: Simplify and increase test coverage

Follows-up I31f1403ab40c79ab270c417.

* Make the test cases less dynamic. It was approaching the same
  kind of complexity as the source code, thus reducing confidence
  in the test.

* Make the test cases more explicit. A good test can be read without
  executing it and show plainly what the expected output are.
  Use little to no indirection, favouring small amounts of
  duplication when in doubt.

* Increase coverage of the "non-standard HTTPS port" configuration,
  by removing the two hardcoded assertions for it, in favour of
  including it in the overal test matrix and applying the same set
  of default cases to it as the other configurations under test.

* There are now 306 instead of 2355 generated test cases, but
  the code coverage of UrlUtils.php remains identical
  at 98.28% (171/174 lines).

Change-Id: I755c017964757b9aab5ebeabd80be5664be48798

2 files changed, 89 insertions, 115 deletions

diff --git a/includes/utils/UrlUtils.php b/includes/utils/UrlUtils.php
index 55b89e400ee1..f21b9e734d59 100644
--- a/includes/utils/UrlUtils.php
+++ b/includes/utils/UrlUtils.php
@@ -144,7 +144,8 @@ class UrlUtils {
 				$defaultProto = $serverProto ?? PROTO_HTTP;
 			}
 
-			$defaultProtoWithoutSlashes = $defaultProto === null ? '' : substr( $defaultProto, 0, -2 );
+			// @phan-suppress-next-line PhanTypeMismatchArgumentNullableInternal T308355
+			$defaultProtoWithoutSlashes = $defaultProto === PROTO_FALLBACK ? '' : substr( $defaultProto, 0, -2 );
 
 			if ( substr( $url, 0, 2 ) == '//' ) {
 				$url = $defaultProtoWithoutSlashes . $url;
diff --git a/tests/phpunit/unit/includes/utils/UrlUtilsProviders.php b/tests/phpunit/unit/includes/utils/UrlUtilsProviders.php
index 0c4cc2df659f..65c13c97c358 100644
--- a/tests/phpunit/unit/includes/utils/UrlUtilsProviders.php
+++ b/tests/phpunit/unit/includes/utils/UrlUtilsProviders.php
@@ -45,132 +45,105 @@ class UrlUtilsProviders {
 		];
 	}
 
-	/**
-	 * Helper method to reduce nesting in provideExpand()
-	 *
-	 * @return Generator
-	 */
-	private static function provideExpandCases(): Generator {
+	public static function provideExpand() {
+		$modes = [ 'http', 'https' ];
 		$servers = [
 			'http://example.com',
 			'https://example.com',
 			'//example.com',
 		];
+		$defaultProtos = [
+			'http' => PROTO_HTTP,
+			'https' => PROTO_HTTPS,
+			'protocol-relative' => PROTO_RELATIVE,
+			'fallback' => PROTO_FALLBACK,
+			'canonical' => PROTO_CANONICAL,
+		];
 
-		foreach ( $servers as $server ) {
-			foreach ( [ 'http://example2.com', 'https://example2.com' ] as $canServer ) {
-				foreach ( [ 'http://internal.com', 'https://internal.com' ] as $intServer ) {
-					foreach ( [ 'http', 'https' ] as $fallbackProto ) {
-						foreach ( [ 111, 443 ] as $httpsPort ) {
-							$options = [
-								UrlUtils::SERVER => $server,
-								UrlUtils::CANONICAL_SERVER => $canServer,
-								UrlUtils::INTERNAL_SERVER => $intServer,
-								UrlUtils::FALLBACK_PROTOCOL => $fallbackProto,
-								UrlUtils::HTTPS_PORT => $httpsPort,
-							];
-							foreach ( self::DEFAULT_PROTOS as $protoDesc => $defaultProto ) {
-								yield [ $options, $protoDesc, $defaultProto ];
-							}
+		foreach ( $modes as $fallbackProto ) {
+			foreach ( $servers as $server ) {
+				foreach ( $modes as $canServerMode ) {
+					$canServer = "$canServerMode://example2.com";
+					$options = [
+						UrlUtils::SERVER => $server,
+						UrlUtils::CANONICAL_SERVER => $canServer,
+						UrlUtils::HTTPS_PORT => 443,
+						UrlUtils::FALLBACK_PROTOCOL => $fallbackProto,
+					];
+					foreach ( $defaultProtos as $protoDesc => $defaultProto ) {
+						$case = "fallback: $fallbackProto, default: $protoDesc, server: $server, canonical: $canServer";
+						yield "No-op fully-qualified http URL ($case)" => [
+							'http://example.com',
+							$options, $defaultProto,
+							'http://example.com',
+						];
+						yield "No-op fully-qualified https URL ($case)" => [
+							'https://example.com',
+							$options, $defaultProto,
+							'https://example.com',
+						];
+						yield "No-op rootless path-only URL ($case" => [
+							"wiki/FooBar",
+							$options, $defaultProto,
+							'wiki/FooBar',
+						];
+
+						// Determine expected protocol
+						if ( $protoDesc === 'protocol-relative' ) {
+							$p = '';
+						} elseif ( $protoDesc === 'fallback' ) {
+							$p = "$fallbackProto:";
+						} elseif ( $protoDesc === 'canonical' ) {
+							$p = "$canServerMode:";
+						} else {
+							$p = $protoDesc . ':';
+						}
+						yield "Expand protocol-relative URL ($case)" => [
+							'//wikipedia.org',
+							$options, $defaultProto,
+							"$p//wikipedia.org",
+						];
+
+						// Determine expected server name
+						if ( $protoDesc === 'canonical' ) {
+							$srv = $canServer;
+						} elseif ( $server === '//example.com' ) {
+							$srv = $p . $server;
+						} else {
+							$srv = $server;
 						}
+						yield "Expand path that starts with slash ($case)" => [
+							'/wiki/FooBar',
+							$options, $defaultProto,
+							"$srv/wiki/FooBar",
+						];
 					}
 				}
 			}
 		}
-	}
-
-	public static function provideExpand(): Generator {
-		$modes = [ 'http', 'https' ];
-
-		foreach ( self::provideExpandCases() as [ $options, $protoDesc, $defaultProto ] ) {
-			$case = "default: $protoDesc";
-			foreach ( $options as $key => $val ) {
-				$case .= ", $key: $val";
-			}
-
-			yield "No-op fully-qualified http URL ($case)" => [
-				'http://example.com',
-				$options, $defaultProto,
-				'http://example.com',
-			];
-			yield "No-op fully-qualified https URL ($case)" => [
-				'https://example.com',
-				$options, $defaultProto,
-				'https://example.com',
-			];
-			yield "No-op fully-qualified https URL with port ($case)" => [
-				'https://example.com:222',
-				$options, $defaultProto,
-				'https://example.com:222',
-			];
-			yield "No-op fully-qualified https URL with standard port ($case)" => [
-				'https://example.com:443',
-				$options, $defaultProto,
-				'https://example.com:443',
-			];
-			yield "No-op rootless path-only URL ($case)" => [
-				"wiki/FooBar",
-				$options, $defaultProto,
-				'wiki/FooBar',
-			];
-
-			// Determine expected protocol
-			switch ( $protoDesc ) {
-				case 'protocol-relative':
-					$p = '';
-					break;
 
-				case 'fallback':
-				case 'current':
-					$p = $options[UrlUtils::FALLBACK_PROTOCOL] . ':';
-					break;
-
-				case 'canonical':
-					$p = strtok( $options[UrlUtils::CANONICAL_SERVER], ':' ) . ':';
-					break;
-
-				case 'internal':
-					$p = strtok( $options[UrlUtils::INTERNAL_SERVER], ':' ) . ':';
-					break;
-
-				case 'http':
-				case 'https':
-					$p = "$protoDesc:";
-			}
-			yield "Expand protocol-relative URL ($case)" => [
-				'//wikipedia.org',
-				$options, $defaultProto,
-				"$p//wikipedia.org",
-			];
-
-			// Determine expected server name
-			if ( $protoDesc === 'canonical' ) {
-				$srv = $options[UrlUtils::CANONICAL_SERVER];
-			} elseif ( $protoDesc === 'internal' ) {
-				$srv = $options[UrlUtils::INTERNAL_SERVER];
-			} elseif ( substr( $options[UrlUtils::SERVER], 0, 2 ) === '//' ) {
-				$srv = $p . $options[UrlUtils::SERVER];
-			} else {
-				$srv = $options[UrlUtils::SERVER];
-			}
-
-			// Add a port only if it's not the default port, the server
-			// protocol is relative, and we're actually trying to produce an
-			// HTTPS URL
-			if ( $options[UrlUtils::HTTPS_PORT] !== 443 &&
-				substr( $options[UrlUtils::SERVER], 0, 2 ) === '//' &&
-				( $defaultProto === PROTO_HTTPS || ( $defaultProto === PROTO_FALLBACK &&
-					$options[UrlUtils::FALLBACK_PROTOCOL] === 'https' ) )
-			) {
-				$srv .= ':' . $options[UrlUtils::HTTPS_PORT];
-			}
-
-			yield "Expand path that starts with slash ($case)" => [
-				'/wiki/FooBar',
-				$options, $defaultProto,
-				"$srv/wiki/FooBar",
-			];
-		}
+		// Non-standard https port
+		$optionsRel111 = [
+			UrlUtils::SERVER => '//wiki.example.com',
+			UrlUtils::CANONICAL_SERVER => 'http://wiki.example.com',
+			UrlUtils::HTTPS_PORT => 111,
+			UrlUtils::FALLBACK_PROTOCOL => 'https',
+		];
+		yield "No-op foreign URL, ignore custom port config" => [
+			'https://foreign.example.com/foo',
+			$optionsRel111, PROTO_HTTPS,
+			'https://foreign.example.com/foo',
+		];
+		yield "No-op foreign URL, preserve existing port" => [
+			'https://foreign.example.com:222/foo',
+			$optionsRel111, PROTO_HTTPS,
+			'https://foreign.example.com:222/foo',
+		];
+		yield "Expand path with custom HTTPS port" => [
+			'/foo',
+			$optionsRel111, PROTO_HTTPS,
+			'https://wiki.example.com:111/foo',
+		];
 
 		// Silly corner cases
 		yield 'CanonicalServer with no protocol' => [