Add assignability tests for initialised parameters

Author: sandersn

tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.js

@@ -18,10 +18,12 @@ function foo2(x = "string", b: number) {
 
 function foo3(x: string | undefined = "string", b: number) {
     x.length; // ok, should be string
+    x = undefined;
 }
 
 function foo4(x: string | undefined = undefined, b: number) {
     x; // should be string | undefined
+    x = undefined;
 }
 
 
@@ -72,10 +74,12 @@ function foo2(x, b) {
 function foo3(x, b) {
     if (x === void 0) { x = "string"; }
     x.length; // ok, should be string
+    x = undefined;
 }
 function foo4(x, b) {
     if (x === void 0) { x = undefined; }
     x; // should be string | undefined
+    x = undefined;
 }
 // .d.ts should have `string | undefined` for foo1, foo2, foo3 and foo4
 foo1(undefined, 1);

tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.symbols

@@ -66,16 +66,24 @@ function foo3(x: string | undefined = "string", b: number) {
 >x.length : Symbol(String.length, Decl(lib.d.ts, --, --))
 >x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 17, 14))
 >length : Symbol(String.length, Decl(lib.d.ts, --, --))
+
+    x = undefined;
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 17, 14))
+>undefined : Symbol(undefined)
 }
 
 function foo4(x: string | undefined = undefined, b: number) {
->foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 19, 1))
->x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 21, 14))
+>foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 20, 1))
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 14))
 >undefined : Symbol(undefined)
->b : Symbol(b, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 21, 48))
+>b : Symbol(b, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 48))
 
     x; // should be string | undefined
->x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 21, 14))
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 14))
+
+    x = undefined;
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 22, 14))
+>undefined : Symbol(undefined)
 }
 
 
@@ -94,40 +102,40 @@ foo3(undefined, 1);
 >undefined : Symbol(undefined)
 
 foo4(undefined, 1);
->foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 19, 1))
+>foo4 : Symbol(foo4, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 20, 1))
 >undefined : Symbol(undefined)
 
 
 function removeUndefinedButNotFalse(x = true) {
->removeUndefinedButNotFalse : Symbol(removeUndefinedButNotFalse, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 31, 19))
->x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 34, 36))
+>removeUndefinedButNotFalse : Symbol(removeUndefinedButNotFalse, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 33, 19))
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 36, 36))
 
     if (x === false) {
->x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 34, 36))
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 36, 36))
 
         return x;
->x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 34, 36))
+>x : Symbol(x, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 36, 36))
     }
 }
 
 declare const cond: boolean;
->cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 40, 13))
+>cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 42, 13))
 
 function removeNothing(y = cond ? true : undefined) {
->removeNothing : Symbol(removeNothing, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 40, 28))
->y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
->cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 40, 13))
+>removeNothing : Symbol(removeNothing, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 42, 28))
+>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
+>cond : Symbol(cond, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 42, 13))
 >undefined : Symbol(undefined)
 
     if (y !== undefined) {
->y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
+>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
 >undefined : Symbol(undefined)
 
         if (y === false) {
->y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
+>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
 
             return y;
->y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 41, 23))
+>y : Symbol(y, Decl(defaultParameterAddsUndefinedWithStrictNullChecks.ts, 43, 23))
         }
     }
     return true;

tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.types

@@ -86,14 +86,19 @@ function foo2(x = "string", b: number) {
 
 function foo3(x: string | undefined = "string", b: number) {
 >foo3 : (x: string | undefined, b: number) => void
->x : string
+>x : string | undefined
 >"string" : "string"
 >b : number
 
     x.length; // ok, should be string
 >x.length : number
 >x : string
 >length : number
+
+    x = undefined;
+>x = undefined : undefined
+>x : string | undefined
+>undefined : undefined
 }
 
 function foo4(x: string | undefined = undefined, b: number) {
@@ -104,6 +109,11 @@ function foo4(x: string | undefined = undefined, b: number) {
 
     x; // should be string | undefined
 >x : string | undefined
+
+    x = undefined;
+>x = undefined : undefined
+>x : string | undefined
+>undefined : undefined
 }
 
 

tests/cases/compiler/defaultParameterAddsUndefinedWithStrictNullChecks.ts

@@ -19,10 +19,12 @@ function foo2(x = "string", b: number) {
 
 function foo3(x: string | undefined = "string", b: number) {
     x.length; // ok, should be string
+    x = undefined;
 }
 
 function foo4(x: string | undefined = undefined, b: number) {
     x; // should be string | undefined
+    x = undefined;
 }