Analyzer: prep file_system tests for null safety.

Fields initialized in `setUp` are late.

Variables initialized with implicit casts like:

    ClassDeclaration clazz = unit.declarations[0];

would need a cast:

    ClassDeclaration clazz = unit.declarations[0] as ClassDeclaration;

so they are updated to use var, which is more idiomatic:

    var clazz = unit.declarations[0] as ClassDeclaration;

Change-Id: I4e4ae814a814d3a4200c5078a6904dbac0a8140c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/170520
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analyzer/test/dart/ast/ast_test.dart

@@ -961,29 +961,29 @@ E f() => g;
   }
 
   void test_findPrevious_basic_class() {
-    ClassDeclaration clazz = unit.declarations[0];
+    var clazz = unit.declarations[0] as ClassDeclaration;
     expect(clazz.findPrevious(findToken('A')).lexeme, 'class');
   }
 
   void test_findPrevious_basic_method() {
-    ClassDeclaration clazz = unit.declarations[0];
-    MethodDeclaration method = clazz.members[0];
+    var clazz = unit.declarations[0] as ClassDeclaration;
+    var method = clazz.members[0] as MethodDeclaration;
     expect(method.findPrevious(findToken('foo')).lexeme, 'B');
   }
 
   void test_findPrevious_basic_statement() {
-    ClassDeclaration clazz = unit.declarations[0];
-    MethodDeclaration method = clazz.members[0];
-    BlockFunctionBody body = method.body;
+    var clazz = unit.declarations[0] as ClassDeclaration;
+    var method = clazz.members[0] as MethodDeclaration;
+    var body = method.body as BlockFunctionBody;
     Statement statement = body.block.statements[0];
     expect(statement.findPrevious(findToken('bar')).lexeme, 'return');
     expect(statement.findPrevious(findToken(';')).lexeme, 'bar');
   }
 
   void test_findPrevious_missing() {
-    ClassDeclaration clazz = unit.declarations[0];
-    MethodDeclaration method = clazz.members[0];
-    BlockFunctionBody body = method.body;
+    var clazz = unit.declarations[0] as ClassDeclaration;
+    var method = clazz.members[0] as MethodDeclaration;
+    var body = method.body as BlockFunctionBody;
     Statement statement = body.block.statements[0];
 
     GatheringErrorListener listener = GatheringErrorListener(checkRanges: true);
@@ -1000,15 +1000,15 @@ E f() => g;
   }
 
   void test_findPrevious_parent_method() {
-    ClassDeclaration clazz = unit.declarations[0];
-    MethodDeclaration method = clazz.members[0];
+    var clazz = unit.declarations[0] as ClassDeclaration;
+    var method = clazz.members[0] as MethodDeclaration;
     expect(method.findPrevious(findToken('B')).lexeme, '{');
   }
 
   void test_findPrevious_parent_statement() {
-    ClassDeclaration clazz = unit.declarations[0];
-    MethodDeclaration method = clazz.members[0];
-    BlockFunctionBody body = method.body;
+    var clazz = unit.declarations[0] as ClassDeclaration;
+    var method = clazz.members[0] as MethodDeclaration;
+    var body = method.body as BlockFunctionBody;
     Statement statement = body.block.statements[0];
     expect(statement.findPrevious(findToken('return')).lexeme, '{');
   }
@@ -1019,8 +1019,8 @@ E f() => g;
   }
 
   void test_findPrevious_sibling_method() {
-    ClassDeclaration clazz = unit.declarations[0];
-    MethodDeclaration method = clazz.members[1];
+    var clazz = unit.declarations[0] as ClassDeclaration;
+    var method = clazz.members[1] as MethodDeclaration;
     expect(method.findPrevious(findToken('D')).lexeme, '}');
   }
 }

pkg/analyzer/test/error/error_test.dart

@@ -39,12 +39,13 @@ class ErrorCodeValuesTest extends ParserTestCase {
             extendsClause.superclass.name.name == 'ErrorCode') {
           String className = declaration.name.name;
           for (ClassMember member in declaration.members) {
-            if (member is FieldDeclaration &&
-                member.isStatic &&
-                (member.fields.type == null ? bad() : true) &&
-                member.fields.type.toSource() == className) {
-              String fieldName = member.fields.variables[0].name.name;
-              declaredCodes.add(className + '.' + fieldName);
+            if (member is FieldDeclaration && member.isStatic) {
+              var fields = member.fields;
+              if ((fields.type == null ? bad() : true) &&
+                  fields.type.toSource() == className) {
+                String fieldName = fields.variables[0].name.name;
+                declaredCodes.add(className + '.' + fieldName);
+              }
             }
           }
         }
@@ -63,7 +64,7 @@ class ErrorCodeValuesTest extends ParserTestCase {
                 member.variables.variables[0].name.name == 'errorCodeValues',
             orElse: () => null);
     ListLiteral listLiteral = declaration.variables.variables[0].initializer;
-    for (PrefixedIdentifier element in listLiteral.elements) {
+    for (var element in listLiteral.elements.cast<PrefixedIdentifier>()) {
       listedCodes.add(element.name);
     }
     return listedCodes;

pkg/analyzer/test/file_system/file_system_test_support.dart

@@ -19,17 +19,17 @@ abstract class FileSystemTestSupport {
   String get defaultFileContent;
 
   /// A path to a file within the [defaultFolderPath] that can be used by tests.
-  String get defaultFilePath;
+  String /*!*/ get defaultFilePath;
 
   /// A path to a folder within the [tempPath] that can be used by tests.
-  String get defaultFolderPath;
+  String /*!*/ get defaultFolderPath;
 
   /// Return the resource provider to be used by the tests.
   ResourceProvider get provider;
 
   /// The absolute path to the temporary directory in which all of the tests are
   /// to work.
-  String get tempPath;
+  String /*!*/ get tempPath;
 
   /// Return a file accessed through the resource provider. If [exists] is
   /// `true` then the returned file will exist, otherwise it won't. If [content]

pkg/analyzer/test/file_system/memory_file_system_test.dart

@@ -34,15 +34,15 @@ abstract class BaseTest extends FileSystemTestSupport {
   /// The absolute path to the temporary directory in which all of the tests are
   /// to work.
   @override
-  String tempPath;
+  /*late*/ String tempPath;
 
   /// A path to a folder within the [tempPath] that can be used by tests.
   @override
-  String defaultFolderPath;
+  /*late*/ String defaultFolderPath;
 
   /// A path to a file within the [defaultFolderPath] that can be used by tests.
   @override
-  String defaultFilePath;
+  /*late*/ String defaultFilePath;
 
   /// The content used for the file at the [defaultFilePath] if it is created
   /// and no other content is provided.

pkg/analyzer/test/file_system/overlay_file_system_test.dart

@@ -819,11 +819,11 @@ class OverlayResourceProviderTest extends OverlayTestSupport {
 }
 
 class OverlayTestSupport {
-  MemoryResourceProvider baseProvider;
-  OverlayResourceProvider provider;
+  /*late*/ MemoryResourceProvider baseProvider;
+  /*late*/ OverlayResourceProvider provider;
 
-  String defaultFolderPath;
-  String defaultFilePath;
+  /*late*/ String defaultFolderPath;
+  /*late*/ String defaultFilePath;
 
   void setUp() {
     baseProvider = MemoryResourceProvider();

pkg/analyzer/test/file_system/physical_file_system_test.dart

@@ -29,20 +29,20 @@ abstract class BaseTest extends FileSystemTestSupport {
 
   /// A temporary directory on disk. All files and folders created by the tests
   /// should be inside this directory.
-  io.Directory tempDirectory;
+  /*late*/ io.Directory tempDirectory;
 
   /// The absolute path to the [tempDirectory]. This path will contain a
   /// symbolic link on some operating systems.
   @override
-  String tempPath;
+  /*late*/ String tempPath;
 
   /// A path to a folder within the [tempDirectory] that can be used by tests.
   @override
-  String defaultFolderPath;
+  /*late*/ String defaultFolderPath;
 
   /// A path to a file within the [defaultFolderPath] that can be used by tests.
   @override
-  String defaultFilePath;
+  /*late*/ String defaultFilePath;
 
   /// The content used for the file at the [defaultFilePath] if it is created
   /// and no other content is provided.

pkg/analyzer/test/file_system/resource_uri_resolver_test.dart

@@ -16,7 +16,7 @@ main() {
 
 @reflectiveTest
 class ResourceUriResolverTest with ResourceProviderMixin {
-  ResourceUriResolver resolver;
+  /*late*/ ResourceUriResolver resolver;
 
   void setUp() {
     resolver = ResourceUriResolver(resourceProvider);