adds an option to "no-unnecessary-type-assertion" rule to ignore (#3257)

palantir · Oct 6, 2017 · c55e3c8 · c55e3c8
1 parent cef6ec5
commit c55e3c8
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Showing 4 changed files with 23 additions and 8 deletions.
diff --git a/src/rules/noUnnecessaryTypeAssertionRule.ts b/src/rules/noUnnecessaryTypeAssertionRule.ts
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import { isObjectFlagSet, isObjectType, isTypeFlagSet } from "tsutils";
+import { isAssertionExpression, isObjectFlagSet, isObjectType, isTypeFlagSet } from "tsutils";
 import * as ts from "typescript";
 import * as Lint from "../index";
 
@@ -24,8 +24,14 @@ export class Rule extends Lint.Rules.TypedRule {
     public static metadata: Lint.IRuleMetadata = {
         ruleName: "no-unnecessary-type-assertion",
         description: "Warns if a type assertion does not change the type of an expression.",
-        options: null,
-        optionsDescription: "Not configurable",
+        options: {
+            type: "list",
+            listType: {
+                type: "array",
+                items: {type: "string"},
+            },
+        },
+        optionsDescription: "A list of whitelisted assertion types to ignore",
         type: "typescript",
         hasFix: true,
         typescriptOnly: true,
@@ -36,13 +42,13 @@ export class Rule extends Lint.Rules.TypedRule {
     public static FAILURE_STRING = "This assertion is unnecessary since it does not change the type of the expression.";
 
     public applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
-        return this.applyWithWalker(new Walker(sourceFile, this.ruleName, program.getTypeChecker()));
+        return this.applyWithWalker(new Walker(sourceFile, this.ruleName, this.ruleArguments, program.getTypeChecker()));
     }
 }
 
-class Walker extends Lint.AbstractWalker<void> {
-    constructor(sourceFile: ts.SourceFile, ruleName: string, private readonly checker: ts.TypeChecker) {
-        super(sourceFile, ruleName, undefined);
+class Walker extends Lint.AbstractWalker<string[]> {
+    constructor(sourceFile: ts.SourceFile, ruleName: string, options: string[], private readonly checker: ts.TypeChecker) {
+        super(sourceFile, ruleName, options);
     }
 
     public walk(sourceFile: ts.SourceFile) {
@@ -61,6 +67,9 @@ class Walker extends Lint.AbstractWalker<void> {
     }
 
     private verifyCast(node: ts.TypeAssertion | ts.NonNullExpression | ts.AsExpression) {
+        if (isAssertionExpression(node) && this.options.indexOf(node.type.getText(this.sourceFile)) !== -1) {
+            return;
+        }
         const castType = this.checker.getTypeAtLocation(node);
         if (castType === undefined) {
             return;

diff --git a/test/rules/no-unnecessary-type-assertion/test.ts.fix b/test/rules/no-unnecessary-type-assertion/test.ts.fix
@@ -1,6 +1,8 @@
 const nonNullStringLiteral: 'test';
 const nonNullString: string;
 const nullableString: string|undefined;
+let anyType: any;
+type AnyDuringMigration = any;
 
 // non-null
 let a = nonNullStringLiteral;
@@ -41,6 +43,7 @@ let q = value1;
 let r = <Iface2>value1;
 let s = value2;
 let t = value2 as Iface1;
+let aa = anyType as AnyDuringMigration;
 
 interface TypeA {
     kind: 'a';

diff --git a/test/rules/no-unnecessary-type-assertion/test.ts.lint b/test/rules/no-unnecessary-type-assertion/test.ts.lint
@@ -1,6 +1,8 @@
 const nonNullStringLiteral: 'test';
 const nonNullString: string;
 const nullableString: string|undefined;
+let anyType: any;
+type AnyDuringMigration = any;
 
 // non-null
 let a = nonNullStringLiteral!;
@@ -54,6 +56,7 @@ let r = <Iface2>value1;
 let s = value2 as Iface2;
         ~~~~~~~~~~~~~~~~  [This assertion is unnecessary since it does not change the type of the expression.]
 let t = value2 as Iface1;
+let aa = anyType as AnyDuringMigration;
 
 interface TypeA {
     kind: 'a';

diff --git a/test/rules/no-unnecessary-type-assertion/tslint.json b/test/rules/no-unnecessary-type-assertion/tslint.json
@@ -1,5 +1,5 @@
 {
   "rules": {
-    "no-unnecessary-type-assertion": true
+    "no-unnecessary-type-assertion": [true, "AnyDuringMigration"]
   }
 }