Address comments

Author: devversion

src/cdk/collections/selection.spec.ts

@@ -1,4 +1,4 @@
-import {SelectionModel} from './selection';
+import {getMultipleValuesInSingleSelectionError, SelectionModel} from './selection';
 
 
 describe('SelectionModel', () => {
@@ -23,8 +23,7 @@ describe('SelectionModel', () => {
     });
 
     it('should throw an error if multiple values are passed to model', () => {
-      expect(() => model.select(1, 2))
-        .toThrowError(/Cannot pass multiple values into SelectionModel with single-value mode/);
+      expect(() => model.select(1, 2)).toThrow(getMultipleValuesInSingleSelectionError());
     });
 
     it('should only preselect one value', () => {

src/cdk/collections/selection.ts

@@ -57,7 +57,7 @@ export class SelectionModel<T> {
    * Selects a value or an array of values.
    */
   select(...values: T[]): void {
-    this._warnMultipleValuesForSingleSelection(values);
+    this._verifyValueAssignment(values);
     values.forEach(value => this._markSelected(value));
     this._emitChangeEvent();
   }
@@ -66,7 +66,7 @@ export class SelectionModel<T> {
    * Deselects a value or an array of values.
    */
   deselect(...values: T[]): void {
-    this._warnMultipleValuesForSingleSelection(values);
+    this._verifyValueAssignment(values);
     values.forEach(value => this._unmarkSelected(value));
     this._emitChangeEvent();
   }
@@ -165,10 +165,13 @@ export class SelectionModel<T> {
     }
   }
 
-  /** Throws an error if multiple values are passed into a selection model with a single value. */
-  private _warnMultipleValuesForSingleSelection(values: T[]) {
+  /**
+   * Verifies the value assignment and throws an error if the specified value array is
+   * including multiple values while the selection model is not supporting multiple values.
+   */
+  private _verifyValueAssignment(values: T[]) {
     if (values.length > 1 && !this._isMulti) {
-      throwMultipleValuesInSingleSelectionError();
+      throw getMultipleValuesInSingleSelectionError();
     }
   }
 }
@@ -182,6 +185,6 @@ export class SelectionChange<T> {
 }
 
 /** Throws an error if multiple values are passed into a selection model with a single value. */
-export function throwMultipleValuesInSingleSelectionError() {
-  throw Error('Cannot pass multiple values into SelectionModel with single-value mode.');
+export function getMultipleValuesInSingleSelectionError() {
+  return Error('Cannot pass multiple values into SelectionModel with single-value mode.');
 }