Add asBool() method

Summary:
Changelog:
[General][Added] - Add asBool() method to JSI

Reviewed By: mhorowitz

Differential Revision: D34630901

fbshipit-source-id: 3007784618fcc0f7828eee42de5cbf2bd71258c5

Author: appden

ReactCommon/jsi/jsi/jsi.cpp

@@ -283,6 +283,15 @@ bool Value::strictEquals(Runtime& runtime, const Value& a, const Value& b) {
   return false;
 }
 
+bool Value::asBool() const {
+  if (!isBool()) {
+    throw JSINativeException(
+        "Value is " + kindToString(*this) + ", expected a boolean");
+  }
+
+  return getBool();
+}
+
 double Value::asNumber() const {
   if (!isNumber()) {
     throw JSINativeException(

ReactCommon/jsi/jsi/jsi.h

@@ -1078,6 +1078,10 @@ class JSI_EXPORT Value {
     return data_.boolean;
   }
 
+  /// \return the boolean value, or throws JSIException if not a
+  /// boolean.
+  bool asBool() const;
+
   /// \return the number value, or asserts if not a number.
   double getNumber() const {
     assert(isNumber());

ReactCommon/jsi/jsi/test/testlib.cpp

@@ -849,6 +849,8 @@ TEST_P(JSITest, ValueTest) {
   EXPECT_EQ(eval("'str'").getString(rt).utf8(rt), "str");
   EXPECT_TRUE(eval("[]").getObject(rt).isArray(rt));
 
+  EXPECT_TRUE(eval("true").asBool());
+  EXPECT_THROW(eval("123").asBool(), JSIException);
   EXPECT_EQ(eval("456").asNumber(), 456);
   EXPECT_THROW(eval("'word'").asNumber(), JSIException);
   EXPECT_EQ(