diff --git a/packages/language-service/ivy/test/diagnostic_spec.ts b/packages/language-service/ivy/test/diagnostic_spec.ts
index 5ebeb615b8..45eeb72e2f 100644
--- a/packages/language-service/ivy/test/diagnostic_spec.ts
+++ b/packages/language-service/ivy/test/diagnostic_spec.ts
@@ -26,13 +26,13 @@ describe('diagnostic', () => {
   });
 
   it('should report member does not exist', () => {
-    const content = service.overwriteInlineTemplate(APP_COMPONENT, '{{ nope }}');
+    const {text} = service.overwriteInlineTemplate(APP_COMPONENT, '{{ nope }}');
     const diags = ngLS.getSemanticDiagnostics(APP_COMPONENT);
     expect(diags.length).toBe(1);
     const {category, file, start, length, messageText} = diags[0];
     expect(category).toBe(ts.DiagnosticCategory.Error);
     expect(file?.fileName).toBe(APP_COMPONENT);
-    expect(content.substring(start!, start! + length!)).toBe('nope');
+    expect(text.substring(start!, start! + length!)).toBe('nope');
     expect(messageText).toBe(`Property 'nope' does not exist on type 'AppComponent'.`);
   });
 });
diff --git a/packages/language-service/ivy/test/mock_host.ts b/packages/language-service/ivy/test/mock_host.ts
index 8541399306..152c2200f4 100644
--- a/packages/language-service/ivy/test/mock_host.ts
+++ b/packages/language-service/ivy/test/mock_host.ts
@@ -105,6 +105,17 @@ export function setup() {
   };
 }
 
+interface OverwriteResult {
+  /**
+   * Position of the cursor, -1 if there isn't one.
+   */
+  position: number;
+  /**
+   * Overwritten content without the cursor.
+   */
+  text: string;
+}
+
 class MockService {
   private readonly overwritten = new Set<ts.server.NormalizedPath>();
 
@@ -113,20 +124,32 @@ class MockService {
       private readonly ps: ts.server.ProjectService,
   ) {}
 
-  overwrite(fileName: string, newText: string): string {
+  /**
+   * Overwrite the entire content of `fileName` with `newText`. If cursor is
+   * present in `newText`, it will be removed and the position of the cursor
+   * will be returned.
+   */
+  overwrite(fileName: string, newText: string): OverwriteResult {
     const scriptInfo = this.getScriptInfo(fileName);
-    this.overwriteScriptInfo(scriptInfo, preprocess(newText));
-    return newText;
+    return this.overwriteScriptInfo(scriptInfo, newText);
   }
 
-  overwriteInlineTemplate(fileName: string, newTemplate: string): string {
+  /**
+   * Overwrite an inline template defined in `fileName` and return the entire
+   * content of the source file (not just the template). If a cursor is present
+   * in `newTemplate`, it will be removed and the position of the cursor in the
+   * source file will be returned.
+   */
+  overwriteInlineTemplate(fileName: string, newTemplate: string): OverwriteResult {
     const scriptInfo = this.getScriptInfo(fileName);
     const snapshot = scriptInfo.getSnapshot();
-    const originalContent = snapshot.getText(0, snapshot.getLength());
-    const newContent =
-        originalContent.replace(/template: `([\s\S]+)`/, `template: \`${newTemplate}\``);
-    this.overwriteScriptInfo(scriptInfo, preprocess(newContent));
-    return newContent;
+    const originalText = snapshot.getText(0, snapshot.getLength());
+    const {position, text} =
+        replaceOnce(originalText, /template: `([\s\S]+?)`/, `template: \`${newTemplate}\``);
+    if (position === -1) {
+      throw new Error(`${fileName} does not contain a component with template`);
+    }
+    return this.overwriteScriptInfo(scriptInfo, text);
   }
 
   reset() {
@@ -151,16 +174,37 @@ class MockService {
     return scriptInfo;
   }
 
-  private overwriteScriptInfo(scriptInfo: ts.server.ScriptInfo, newText: string) {
+  /**
+   * Remove the cursor from `newText`, then replace `scriptInfo` with the new
+   * content and return the position of the cursor.
+   * @param scriptInfo
+   * @param newText Text that possibly contains a cursor
+   */
+  private overwriteScriptInfo(scriptInfo: ts.server.ScriptInfo, newText: string): OverwriteResult {
+    const result = replaceOnce(newText, /¦/, '');
     const snapshot = scriptInfo.getSnapshot();
-    scriptInfo.editContent(0, snapshot.getLength(), newText);
+    scriptInfo.editContent(0, snapshot.getLength(), result.text);
     this.overwritten.add(scriptInfo.fileName);
+    return result;
   }
 }
 
-const REGEX_CURSOR = /¦/g;
-function preprocess(text: string): string {
-  return text.replace(REGEX_CURSOR, '');
+/**
+ * Replace at most one occurence that matches `regex` in the specified
+ * `searchText` with the specified `replaceText`. Throw an error if there is
+ * more than one occurrence.
+ */
+function replaceOnce(searchText: string, regex: RegExp, replaceText: string): OverwriteResult {
+  regex = new RegExp(regex.source, regex.flags + 'g' /* global */);
+  let position = -1;
+  const text = searchText.replace(regex, (...args) => {
+    if (position !== -1) {
+      throw new Error(`${regex} matches more than one occurrence in text: ${searchText}`);
+    }
+    position = args[args.length - 2];  // second last argument is always the index
+    return replaceText;
+  });
+  return {position, text};
 }
 
 const REF_MARKER = /«(((\w|\-)+)|([^ᐱ]*ᐱ(\w+)ᐱ.[^»]*))»/g;
diff --git a/packages/language-service/ivy/test/mock_host_spec.ts b/packages/language-service/ivy/test/mock_host_spec.ts
index cb4b3d7427..e12dd112c1 100644
--- a/packages/language-service/ivy/test/mock_host_spec.ts
+++ b/packages/language-service/ivy/test/mock_host_spec.ts
@@ -8,7 +8,7 @@
 
 import * as ts from 'typescript/lib/tsserverlibrary';
 
-import {APP_MAIN, setup, TEST_SRCDIR} from './mock_host';
+import {APP_COMPONENT, APP_MAIN, setup, TEST_SRCDIR} from './mock_host';
 
 describe('mock host', () => {
   const {project, service, tsLS} = setup();
@@ -58,13 +58,93 @@ describe('mock host', () => {
     expect(getText(scriptInfo)).toBe('const x: string = 0');
   });
 
-  it('can find the cursor', () => {
-    const content = service.overwrite(APP_MAIN, `const fo¦o = 'hello world';`);
-    // content returned by overwrite() is the original content with cursor
-    expect(content).toBe(`const fo¦o = 'hello world';`);
-    const scriptInfo = service.getScriptInfo(APP_MAIN);
-    // script info content should not contain cursor
-    expect(getText(scriptInfo)).toBe(`const foo = 'hello world';`);
+  describe('overwrite()', () => {
+    it('will return the cursor position', () => {
+      const {position} = service.overwrite(APP_MAIN, `const fo¦o = 'hello world';`);
+      expect(position).toBe(8);
+    });
+
+    it('will remove the cursor in overwritten text', () => {
+      const {text} = service.overwrite(APP_MAIN, `const fo¦o = 'hello world';`);
+      expect(text).toBe(`const foo = 'hello world';`);
+    });
+
+    it('will update script info without cursor', () => {
+      const {text} = service.overwrite(APP_MAIN, `const fo¦o = 'hello world';`);
+      const scriptInfo = service.getScriptInfo(APP_MAIN);
+      const snapshot = getText(scriptInfo);
+      expect(snapshot).toBe(`const foo = 'hello world';`);
+      expect(snapshot).toBe(text);
+    });
+
+    it('will throw if there is more than one cursor', () => {
+      expect(() => service.overwrite(APP_MAIN, `const f¦oo = 'hello wo¦rld';`))
+          .toThrowError(/matches more than one occurrence in text/);
+    });
+
+    it('will return -1 if cursor is not present', () => {
+      const {position} = service.overwrite(APP_MAIN, `const foo = 'hello world';`);
+      expect(position).toBe(-1);
+    });
+  });
+
+  describe('overwriteInlineTemplate()', () => {
+    it('will return the cursor position', () => {
+      const {position, text} = service.overwriteInlineTemplate(APP_COMPONENT, `{{ fo¦o }}`);
+      // The position returned should be relative to the start of the source
+      // file, not the start of the template.
+      expect(position).not.toBe(5);
+      expect(text.substring(position, position + 4)).toBe('o }}');
+    });
+
+    it('will remove the cursor in overwritten text', () => {
+      const {text} = service.overwriteInlineTemplate(APP_COMPONENT, `{{ fo¦o }}`);
+      expect(text).toContain(`{{ foo }}`);
+    });
+
+    it('will return the entire content of the source file', () => {
+      const {text} = service.overwriteInlineTemplate(APP_COMPONENT, `{{ foo }}`);
+      expect(text).toContain(`@Component`);
+    });
+
+    it('will update script info without cursor', () => {
+      service.overwriteInlineTemplate(APP_COMPONENT, `{{ fo¦o }}`);
+      const scriptInfo = service.getScriptInfo(APP_COMPONENT);
+      expect(getText(scriptInfo)).toContain(`{{ foo }}`);
+    });
+
+    it('will throw if there is no template in file', () => {
+      expect(() => service.overwriteInlineTemplate(APP_MAIN, `{{ foo }}`))
+          .toThrowError(/does not contain a component with template/);
+    });
+
+    it('will throw if there is more than one cursor', () => {
+      expect(() => service.overwriteInlineTemplate(APP_COMPONENT, `{{ f¦o¦o }}`))
+          .toThrowError(/matches more than one occurrence in text/);
+    });
+
+    it('will return -1 if cursor is not present', () => {
+      const {position} = service.overwriteInlineTemplate(APP_COMPONENT, `{{ foo }}`);
+      expect(position).toBe(-1);
+    });
+
+    it('will throw if there is more than one component with template', () => {
+      service.overwrite(APP_COMPONENT, `
+        import {Component} from '@angular/core';
+
+        @Component({
+          template: \`<h1></h1>\`,
+        })
+        export class ComponentA {}
+
+        @Component({
+          template: \`<h2></h2>\`,
+        })
+        export class ComponentB {}
+      `);
+      expect(() => service.overwriteInlineTemplate(APP_COMPONENT, `<p></p>`))
+          .toThrowError(/matches more than one occurrence in text/);
+    });
   });
 });