In insertNodeAfter, handle file with no trailing newline

src/harness/fourslash.ts

@@ -2652,10 +2652,10 @@ Actual: ${stringify(fullActual)}`);
         public verifyImportFixAtPosition(expectedTextArray: string[], errorCode: number | undefined, preferences: ts.UserPreferences | undefined) {
             const { fileName } = this.activeFile;
             const ranges = this.getRanges().filter(r => r.fileName === fileName);
-            if (ranges.length !== 1) {
+            if (ranges.length > 1) {
                 this.raiseError("Exactly one range should be specified in the testfile.");
             }
-            const range = ts.first(ranges);
+            const range = ts.firstOrUndefined(ranges);
 
             const codeFixes = this.getCodeFixes(fileName, errorCode, preferences).filter(f => f.fixId === undefined); // TODO: GH#20315 filter out those that use the import fix ID;
 
@@ -2674,7 +2674,7 @@ Actual: ${stringify(fullActual)}`);
                 const change = ts.first(codeFix.changes);
                 ts.Debug.assert(change.fileName === fileName);
                 this.applyEdits(change.fileName, change.textChanges, /*isFormattingEdit*/ false);
-                const text = this.rangeText(range);
+                const text = range ? this.rangeText(range) : this.getFileContent(this.activeFile.fileName);
                 actualTextArray.push(text);
                 scriptInfo.updateContent(originalContent);
             }

src/services/textChanges.ts

@@ -177,10 +177,10 @@ namespace ts.textChanges {
     }
 
     function getAdjustedEndPosition(sourceFile: SourceFile, node: Node, options: ConfigurableEnd) {
+        const { end } = node;
         if (options.useNonAdjustedEndPosition || isExpression(node)) {
-            return node.getEnd();
+            return end;
         }
-        const end = node.getEnd();
         const newEnd = skipTrivia(sourceFile.text, end, /*stopAfterLineBreak*/ true);
         return newEnd !== end && isLineBreak(sourceFile.text.charCodeAt(newEnd - 1))
             ? newEnd
@@ -466,7 +466,11 @@ namespace ts.textChanges {
                 }
             }
             const endPosition = getAdjustedEndPosition(sourceFile, after, {});
-            return this.replaceRange(sourceFile, createTextRange(endPosition), newNode, this.getInsertNodeAfterOptions(after));
+            const options = this.getInsertNodeAfterOptions(after);
+            return this.replaceRange(sourceFile, createTextRange(endPosition), newNode, {
+                ...options,
+                prefix: after.end === sourceFile.end && isStatement(after) ? (options.prefix ? `\n${options.prefix}` : "\n") : options.prefix,
+            });
         }
 
         private getInsertNodeAfterOptions(node: Node): InsertNodeOptions {

tests/baselines/reference/textChanges/insertNodeAfter2.js

@@ -20,6 +20,7 @@ namespace M {
     // comment 6
     var a = 4; // comment 7
 }
+
 public class class1 implements interface1
 {
     property1: boolean;

tests/cases/fourslash/codeFixAddMissingMember5.ts

@@ -18,6 +18,7 @@ verify.codeFix({
         ()=>{ this.foo === 10 };
     }
 }
+
 C.foo = undefined;
 `
 });

tests/cases/fourslash/codeFixAddMissingMember7.ts

@@ -14,6 +14,7 @@ verify.codeFix({
     newFileContent: `class C {
     static p = ()=>{ this.foo === 10 };
 }
+
 C.foo = undefined;
 `
 });

tests/cases/fourslash/convertFunctionToEs6Class_commentOnVariableDeclaration.ts

@@ -8,7 +8,8 @@
 verify.codeFix({
     description: "Convert function to an ES2015 class",
     newFileContent:
-`/** Doc */
+`
+/** Doc */
 class C {
     constructor() { this.x = 0; }
 }

tests/cases/fourslash/importNameCodeFix_fileWithNoTrailingNewline.ts

@@ -0,0 +1,19 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: /a.ts
+////export const foo = 0;
+
+// @Filename: /b.ts
+////export const bar = 0;
+
+// @Filename: /c.ts
+////foo;
+////import { bar } from "./b";
+
+goTo.file("/c.ts");
+verify.importFixAtPosition([
+`foo;
+import { bar } from "./b";
+import { foo } from "./a";
+`,
+]);

tests/cases/fourslash/importNameCodeFix_jsExtension.ts

@@ -13,10 +13,13 @@
 ////import * as g from "global"; // Global imports skipped
 ////import { a } from "./a.js";
 ////import { a as a2 } from "./a"; // Ignored, only the first relative import is considered
-////[|b;|]
+////b;
 
 goTo.file("/c.ts");
 verify.importFixAtPosition([
-`import { b } from "./b.js";
+`import * as g from "global"; // Global imports skipped
+import { a } from "./a.js";
+import { a as a2 } from "./a"; // Ignored, only the first relative import is considered
+import { b } from "./b.js";
 b;`,
 ]);

tests/cases/fourslash/importNameCodeFix_jsx.ts

@@ -13,11 +13,11 @@
 
 // @Filename: /c.tsx
 ////import { React } from "react";
-////[|<Foo />;|]
+////<Foo />;
 
 // @Filename: /d.tsx
-////[|import { Foo } from "./Foo";
-////<Foo />;|]
+////import { Foo } from "./Foo";
+////<Foo />;
 
 // Tests that we don't crash at non-identifier location.
 goTo.file("/a.tsx");
@@ -26,7 +26,8 @@ verify.importFixAtPosition([]);
 // When constructor is missing, provide fix for that
 goTo.file("/c.tsx");
 verify.importFixAtPosition([
-`import { Foo } from "./Foo";
+`import { React } from "react";
+import { Foo } from "./Foo";
 <Foo />;`]);
 
 // When JSX namespace is missing, provide fix for that