From 5715b08c8a3aa6bbfda214c5474028f401a690e6 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Fri, 16 Feb 2018 15:32:58 -0800
Subject: [PATCH] no-unnecessary-type-assertion: Don't check `!` if
 --strictNullChecks is not enabled

---
 src/rules/noUnnecessaryTypeAssertionRule.ts        | 14 +++++++++++---
 .../noStrictNullChecks/test.ts.lint                |  6 ++++++
 .../noStrictNullChecks/tsconfig.json               |  1 +
 .../noStrictNullChecks/tslint.json                 |  5 +++++
 .../{ => strictNullChecks}/test.ts.fix             |  0
 .../{ => strictNullChecks}/test.ts.lint            |  0
 .../{ => strictNullChecks}/tsconfig.json           |  0
 .../{ => strictNullChecks}/tslint.json             |  0
 8 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 test/rules/no-unnecessary-type-assertion/noStrictNullChecks/test.ts.lint
 create mode 100644 test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tsconfig.json
 create mode 100644 test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tslint.json
 rename test/rules/no-unnecessary-type-assertion/{ => strictNullChecks}/test.ts.fix (100%)
 rename test/rules/no-unnecessary-type-assertion/{ => strictNullChecks}/test.ts.lint (100%)
 rename test/rules/no-unnecessary-type-assertion/{ => strictNullChecks}/tsconfig.json (100%)
 rename test/rules/no-unnecessary-type-assertion/{ => strictNullChecks}/tslint.json (100%)

diff --git a/src/rules/noUnnecessaryTypeAssertionRule.ts b/src/rules/noUnnecessaryTypeAssertionRule.ts
index 1a08296975f..7254b6097ae 100644
--- a/src/rules/noUnnecessaryTypeAssertionRule.ts
+++ b/src/rules/noUnnecessaryTypeAssertionRule.ts
@@ -42,12 +42,18 @@ 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, this.ruleArguments, program.getTypeChecker()));
+        return this.applyWithWalker(new Walker(
+            sourceFile, this.ruleName, this.ruleArguments, program.getTypeChecker(), !!program.getCompilerOptions().strictNullChecks));
     }
 }
 
 class Walker extends Lint.AbstractWalker<string[]> {
-    constructor(sourceFile: ts.SourceFile, ruleName: string, options: string[], private readonly checker: ts.TypeChecker) {
+    constructor(
+        sourceFile: ts.SourceFile,
+        ruleName: string,
+        options: string[],
+        private readonly checker: ts.TypeChecker,
+        private readonly strictNullChecks: boolean) {
         super(sourceFile, ruleName, options);
     }
 
@@ -55,7 +61,9 @@ class Walker extends Lint.AbstractWalker<string[]> {
         const cb = (node: ts.Node): void => {
             switch (node.kind) {
                 case ts.SyntaxKind.NonNullExpression:
-                    this.checkNonNullAssertion(node as ts.NonNullExpression);
+                    if (this.strictNullChecks) {
+                        this.checkNonNullAssertion(node as ts.NonNullExpression);
+                    }
                     break;
                 case ts.SyntaxKind.TypeAssertionExpression:
                 case ts.SyntaxKind.AsExpression:
diff --git a/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/test.ts.lint b/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/test.ts.lint
new file mode 100644
index 00000000000..baa6c0a6dfd
--- /dev/null
+++ b/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/test.ts.lint
@@ -0,0 +1,6 @@
+declare const x: string | undefined;
+x!;
+
+declare const y: string;
+y as string;
+~~~~~~~~~~~  [This assertion is unnecessary since it does not change the type of the expression.]
diff --git a/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tsconfig.json b/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tsconfig.json
new file mode 100644
index 00000000000..0967ef424bc
--- /dev/null
+++ b/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tsconfig.json
@@ -0,0 +1 @@
+{}
diff --git a/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tslint.json b/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tslint.json
new file mode 100644
index 00000000000..2acf91b7b08
--- /dev/null
+++ b/test/rules/no-unnecessary-type-assertion/noStrictNullChecks/tslint.json
@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "no-unnecessary-type-assertion": true
+  }
+}
diff --git a/test/rules/no-unnecessary-type-assertion/test.ts.fix b/test/rules/no-unnecessary-type-assertion/strictNullChecks/test.ts.fix
similarity index 100%
rename from test/rules/no-unnecessary-type-assertion/test.ts.fix
rename to test/rules/no-unnecessary-type-assertion/strictNullChecks/test.ts.fix
diff --git a/test/rules/no-unnecessary-type-assertion/test.ts.lint b/test/rules/no-unnecessary-type-assertion/strictNullChecks/test.ts.lint
similarity index 100%
rename from test/rules/no-unnecessary-type-assertion/test.ts.lint
rename to test/rules/no-unnecessary-type-assertion/strictNullChecks/test.ts.lint
diff --git a/test/rules/no-unnecessary-type-assertion/tsconfig.json b/test/rules/no-unnecessary-type-assertion/strictNullChecks/tsconfig.json
similarity index 100%
rename from test/rules/no-unnecessary-type-assertion/tsconfig.json
rename to test/rules/no-unnecessary-type-assertion/strictNullChecks/tsconfig.json
diff --git a/test/rules/no-unnecessary-type-assertion/tslint.json b/test/rules/no-unnecessary-type-assertion/strictNullChecks/tslint.json
similarity index 100%
rename from test/rules/no-unnecessary-type-assertion/tslint.json
rename to test/rules/no-unnecessary-type-assertion/strictNullChecks/tslint.json