no-inferrable-types: Add ignore-params flag

This change allows using no-inferrable types at times when you
may want to still require types for method/function parameter lists
(for example when using the typedef rule)

src/rules/noInferrableTypesRule.ts

@@ -18,6 +18,8 @@
 import * as ts from "typescript";
 import * as Lint from "../lint";
 
+const OPTION_IGNORE_PARMS = "ignore-params";
+
 export class Rule extends Lint.Rules.AbstractRule {
     public static FAILURE_STRING_FACTORY = (type: string) => `LHS type (${type}) inferred by RHS expression, remove type annotation`;
 
@@ -33,7 +35,9 @@ class NoInferrableTypesWalker extends Lint.RuleWalker {
     }
 
     public visitParameterDeclaration(node: ts.ParameterDeclaration) {
-        this.checkDeclaration(node);
+        if (!this.hasOption(OPTION_IGNORE_PARMS)) {
+            this.checkDeclaration(node);
+        }
         super.visitParameterDeclaration(node);
     }
 

test/rules/no-inferrable-types/ignore-params/test.ts.lint

@@ -0,0 +1,32 @@
+// errors, inferrable type is declared
+let x: number = 7;
+       ~~~~~~           [number]
+let y: boolean = false;
+       ~~~~~~~          [boolean]
+let z: string = "foo";
+       ~~~~~~           [string]
+
+// not errors, we are skipping params
+function foo (a: number = 5, b: boolean = true, c: string = "bah") { }
+
+class TestClass {
+   doSomething(a: number = 5, b: boolean = true, c: string = "bah") {}
+}
+
+// not errors, inferrable type is not declared
+let _x = 7;
+let _y = false;
+let _z = "foo";
+
+// not error, type is not inferrable
+let weird: any = 123;
+
+// not errors, inferrable type is not declared
+function bar(a = 5, b = true, c = "bah") { }
+
+// not errors, types are not inferrable
+function baz(a: any = 5, b: any = true, c: any = "bah") { }
+
+[number]: LHS type (number) inferred by RHS expression, remove type annotation
+[boolean]: LHS type (boolean) inferred by RHS expression, remove type annotation
+[string]: LHS type (string) inferred by RHS expression, remove type annotation

test/rules/no-inferrable-types/ignore-params/tslint.json

@@ -0,0 +1,8 @@
+{
+  "rules": {
+    "no-inferrable-types": [
+      true,
+      "ignore-params"
+    ]
+  }
+}