Make use of drop, avoid clone, avoid null pointers

Cargo.toml

@@ -11,3 +11,4 @@ description = "Safe(er) rust wrapper for dukbind."
 
 [dependencies]
 dukbind = { path = "../dukbind" }
+anyhow = "1.0.26"

README.md

@@ -5,6 +5,9 @@
 ## Work In Progress
 This library is a work in progress and is currently limited in features.
 
+ - [ ] Remove `as_number`/`as_str`/`as_*` in general and use `From<T>` trait instead.
+ - [ ] Revisit error handling and maybe change to use `anyhow`.
+
 ## What can it do?
 At the moment, duktape-rs
 

src/lib.rs

@@ -1,10 +1,21 @@
-extern crate dukbind;
-
-use dukbind::*;
+use anyhow;
+use dukbind::{
+    duk_bool_t, duk_context, duk_create_heap_default, duk_del_prop, duk_destroy_heap, duk_dup,
+    duk_eval_string, duk_get_boolean, duk_get_error_code, duk_get_heapptr, duk_get_number,
+    duk_get_prop_lstring, duk_get_string, duk_get_type, duk_int_t, duk_is_undefined,
+    duk_json_decode, duk_json_encode, duk_pop, duk_pop_2, duk_push_boolean, duk_push_heap_stash,
+    duk_push_heapptr, duk_push_lstring, duk_push_nan, duk_push_null, duk_push_number,
+    duk_push_pointer, duk_push_undefined, duk_put_prop, duk_put_prop_lstring, duk_size_t,
+    DUK_ERR_ERROR, DUK_ERR_EVAL_ERROR, DUK_ERR_NONE, DUK_ERR_RANGE_ERROR, DUK_ERR_SYNTAX_ERROR,
+    DUK_ERR_TYPE_ERROR, DUK_ERR_URI_ERROR, DUK_TYPE_BOOLEAN, DUK_TYPE_NONE, DUK_TYPE_NULL,
+    DUK_TYPE_NUMBER, DUK_TYPE_STRING, DUK_TYPE_UNDEFINED,
+};
 use std::error::Error;
-use std::fmt;
 use std::f64;
+use std::ffi::CStr;
+use std::fmt;
 use std::os::raw::c_void;
+use std::ptr::NonNull;
 
 /// An error code representing why an error occurred.
 #[allow(missing_docs)]
@@ -18,220 +29,245 @@ pub enum DukErrorCode {
     Syntax = DUK_ERR_SYNTAX_ERROR,
     Type = DUK_ERR_TYPE_ERROR,
     URI = DUK_ERR_URI_ERROR,
-    NullPtr
+    NullPtr,
 }
 
 /// Represents a JavaScript number value. JavaScript numbers can be either floats or integers, as well as NaN and Infinity.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum DukNumber {
     NaN,
     Infinity,
     Float(f64),
-    Int(i64)
+    Int(i64),
 }
 
 impl DukNumber {
     pub fn as_str(&self) -> String {
-        match self.clone() {
+        match self {
             DukNumber::NaN => "NaN".to_string(),
             DukNumber::Infinity => "Infinity".to_string(),
             DukNumber::Float(v) => v.clone().to_string(),
-            DukNumber::Int(v) => v.clone().to_string()
+            DukNumber::Int(v) => v.clone().to_string(),
         }
     }
+
     pub fn is_f64(&self) -> bool {
         match self {
             DukNumber::Int(_v) => false,
-            _ => true
+            _ => true,
         }
     }
+
     pub fn is_i64(&self) -> bool {
         self.is_f64() == false
     }
+
     pub fn is_nan(&self) -> bool {
         match self {
             DukNumber::NaN => true,
-            _ => false
+            _ => false,
         }
     }
+
     pub fn is_infinity(&self) -> bool {
         match self {
             DukNumber::Infinity => true,
-            _ => false
+            _ => false,
         }
     }
+
     pub fn as_f64(&self) -> f64 {
         match self {
             DukNumber::NaN => f64::NAN,
             DukNumber::Infinity => f64::INFINITY,
             DukNumber::Float(v) => *v,
-            DukNumber::Int(v) => *v as f64
+            DukNumber::Int(v) => *v as f64,
         }
     }
+
     pub fn as_i64(&self) -> i64 {
         match self {
             DukNumber::NaN => f64::NAN as i64,
             DukNumber::Infinity => f64::INFINITY as i64,
             DukNumber::Float(v) => *v as i64,
-            DukNumber::Int(v) => *v
+            DukNumber::Int(v) => *v,
         }
     }
 }
 
 /// A wrapper around duktape's heapptr. These represent JavaScript objects.
-#[derive(Clone, Debug)]
-pub struct DukObject {
-    context: DukContext,
-    heap: *mut c_void
+#[derive(Debug)]
+pub struct DukObject<'a> {
+    context: &'a DukContext,
+    heap: NonNull<c_void>,
 }
 
-impl DukObject {
-    /// Encode this object to a JSON string.
-    pub fn encode(&mut self) -> Option<String> {
-        unsafe {
-            match self.context.ctx {
-                Some(ctx) => {
-                    let idx = duk_push_heapptr(ctx, self.heap);
-                    if duk_is_undefined(ctx, idx) == 0 {
-                        duk_dup(ctx, idx);
-                        let raw = duk_json_encode(ctx, -1);
-                        use std::ffi::CStr;
-                        let t = CStr::from_ptr(raw);
-                        let cow = t.to_string_lossy();
-                        duk_pop_2(ctx);
-                        Some(String::from(cow))
-                    } else {
-                        duk_pop(ctx);
-                        None
-                    }
-                },
-                None => None
-            }
-        }
-    }
+impl<'a> Drop for DukObject<'a> {
     /// Deletes the object from the heap stash and nullifies the internal heap pointer value.
     /// The object value is useless after calling this and should no longer be used.
-    pub fn free(&mut self) {
+    fn drop(&mut self) {
+        let ctx = self.context.ctx.as_ptr();
         unsafe {
-            use std::ptr::null_mut;
-            match self.context.ctx {
-                Some(ctx) => {
-                    duk_push_heap_stash(ctx);
-                    duk_push_pointer(ctx, self.heap);
-                    duk_del_prop(ctx, -2);
-                    duk_pop(ctx);
-                    self.heap = null_mut();
-                },
-                None => ()
-            }
-        }
-    }
-    /// Get a property on this object as a DukValue.
-    pub fn get_prop(&mut self, name: &str) -> DukResult<DukValue> {
-        unsafe {
-            let ctx = self.context.ctx.expect("Invalid context pointer.");
-            let idx = duk_push_heapptr(ctx, self.heap);
-            if duk_get_prop_lstring(ctx, idx, name.as_ptr() as *const i8, name.len() as duk_size_t) == 1 {
-                let result = self.context.get_value();
-                duk_pop(ctx);
-                Ok(result)
-            } else {
-                Err(DukError{ code: DukErrorCode::Error, message: Some("Could not get property.".to_string())})
-            }
-        }
-    }
-    /// Set a property on this object.
-    pub fn set_prop(&mut self, name: &str, value: DukValue) -> DukResult<()> {
-        match self.context.ctx {
-            Some(ctx) => {
-                unsafe {
-                    duk_push_heapptr(ctx, self.heap);
-                    if duk_is_undefined(ctx, -1) == 0 {
-                        let mut ok: bool = true;
-                        match value {
-                            DukValue::Undefined => duk_push_undefined(ctx),
-                            DukValue::Null => duk_push_null(ctx),
-                            DukValue::Number(ref n) => {
-                                if n.is_nan() {
-                                    duk_push_nan(ctx);
-                                } else if n.is_infinity() {
-                                    duk_push_lstring(ctx, "Infinity".as_ptr() as *const i8, "Infinity".len() as duk_size_t);
-                                } else {
-                                    duk_push_number(ctx, n.as_f64());
-                                }
-                            },
-                            DukValue::Boolean(b) => duk_push_boolean(ctx, value.as_duk_bool().expect("Not a boolean!")),
-                            DukValue::String(s) => {
-                                let t = &s;
-                                duk_push_lstring(ctx, t.as_ptr() as *const i8, t.len() as duk_size_t);
-                            },
-                            DukValue::Object(ref o) => {
-                                duk_push_heapptr(ctx, o.heap);
-                                if duk_is_undefined(ctx, -1) == 1 {
-                                    duk_pop(ctx);
-                                    ok = false;
-                                }
-                            }
-                        };
-                        if ok {
-                            if duk_put_prop_lstring(ctx, -2, name.as_ptr() as *const i8, name.len() as duk_size_t) == 1 {
-                                duk_pop(ctx);
-                                Ok(())
-                            } else {
-                                duk_pop(ctx);
-                                Err(DukError::from(DukErrorCode::Error, "Failed to set prop."))
-                            }
-                        } else {
-                            duk_pop(ctx);
-                            Err(DukError::from(DukErrorCode::Error, "Error setting prop."))
-                        }
-                    } else {
-                        duk_pop(ctx);
-                        Err(DukError::from(DukErrorCode::NullPtr, "Invalid heap pointer."))
-                    }
-                }
-            },
-            None => Err(DukError::from(DukErrorCode::NullPtr, "Invalid context pointer."))
+            duk_push_heap_stash(ctx);
+            duk_push_pointer(ctx, self.heap.as_ptr());
+            duk_del_prop(ctx, -2);
+            duk_pop(ctx);
         }
     }
+}
+
+impl<'a> DukObject<'a> {
     /// Creates a new DukObject from the object at the top of the value stack.
-    pub fn new(context: DukContext) -> DukObject {
-        unsafe {
-            let ctx = context.ctx.expect("Invalid context pointer.");
+    pub fn new(context: &'a DukContext) -> Self {
+        let ctx = context.ctx.as_ptr();
+        let heap = unsafe {
             let ptr = duk_get_heapptr(ctx, -1);
             duk_push_heap_stash(ctx);
             duk_push_pointer(ctx, ptr);
             duk_dup(ctx, -3);
             duk_put_prop(ctx, -3);
             duk_pop(ctx);
-            DukObject { heap: ptr, context: context }
+            NonNull::new_unchecked(ptr)
+        };
+
+        Self { heap, context }
+    }
+
+    /// Encode this object to a JSON string.
+    pub fn encode(&self) -> Option<String> {
+        let ctx = self.context.ctx.as_ptr();
+        unsafe {
+            let idx = duk_push_heapptr(ctx, self.heap.as_ptr());
+            if duk_is_undefined(ctx, idx) == 0 {
+                duk_dup(ctx, idx);
+                let raw = duk_json_encode(ctx, -1);
+                let t = CStr::from_ptr(raw);
+                let cow = t.to_string_lossy();
+                duk_pop_2(ctx);
+                Some(String::from(cow))
+            } else {
+                duk_pop(ctx);
+                None
+            }
+        }
+    }
+
+    /// Get a property on this object as a DukValue.
+    pub fn get_prop(&self, name: &str) -> DukResult<DukValue> {
+        let ctx = self.context.ctx.as_ptr();
+        unsafe {
+            let idx = duk_push_heapptr(ctx, self.heap.as_ptr());
+            if duk_get_prop_lstring(
+                ctx,
+                idx,
+                name.as_ptr() as *const i8,
+                name.len() as duk_size_t,
+            ) == 1
+            {
+                let result = self.context.get_value();
+                duk_pop(ctx);
+                Ok(result)
+            } else {
+                Err(DukError {
+                    code: DukErrorCode::Error,
+                    message: Some(String::from("Could not get property.")),
+                })
+            }
+        }
+    }
+
+    /// Set a property on this object.
+    pub fn set_prop(&self, name: &str, value: DukValue) -> DukResult<()> {
+        let ctx = self.context.ctx.as_ptr();
+        unsafe {
+            duk_push_heapptr(ctx, self.heap.as_ptr());
+            if duk_is_undefined(ctx, -1) == 0 {
+                let mut ok = true;
+                match value {
+                    DukValue::Undefined => duk_push_undefined(ctx),
+                    DukValue::Null => duk_push_null(ctx),
+                    DukValue::Number(ref n) => {
+                        if n.is_nan() {
+                            duk_push_nan(ctx);
+                        } else if n.is_infinity() {
+                            let inf = "Infinity";
+                            duk_push_lstring(
+                                ctx,
+                                inf.as_ptr() as *const i8,
+                                inf.len() as duk_size_t,
+                            );
+                        } else {
+                            duk_push_number(ctx, n.as_f64());
+                        }
+                    }
+                    DukValue::Boolean(b) => {
+                        duk_push_boolean(ctx, value.as_duk_bool().expect("Not a boolean!"))
+                    }
+                    DukValue::String(s) => {
+                        let t = &s;
+                        duk_push_lstring(ctx, t.as_ptr() as *const i8, t.len() as duk_size_t);
+                    }
+                    DukValue::Object(ref o) => {
+                        duk_push_heapptr(ctx, o.heap.as_ptr());
+                        if duk_is_undefined(ctx, -1) == 1 {
+                            duk_pop(ctx);
+                            ok = false;
+                        }
+                    }
+                };
+                if ok {
+                    if duk_put_prop_lstring(
+                        ctx,
+                        -2,
+                        name.as_ptr() as *const i8,
+                        name.len() as duk_size_t,
+                    ) == 1
+                    {
+                        duk_pop(ctx);
+                        Ok(())
+                    } else {
+                        duk_pop(ctx);
+                        Err(DukError::from(DukErrorCode::Error, "Failed to set prop."))
+                    }
+                } else {
+                    duk_pop(ctx);
+                    Err(DukError::from(DukErrorCode::Error, "Error setting prop."))
+                }
+            } else {
+                duk_pop(ctx);
+                Err(DukError::from(
+                    DukErrorCode::NullPtr,
+                    "Invalid heap pointer.",
+                ))
+            }
         }
     }
 }
 
 /// Represents a JavaScript value type.
-#[derive(Clone, Debug)]
-pub enum DukValue {
+#[derive(Debug)]
+pub enum DukValue<'a> {
     Undefined,
     Null,
     Number(DukNumber),
     Boolean(bool),
     String(String),
-    Object(DukObject)
+    Object(DukObject<'a>),
 }
 
-impl DukValue {
+impl<'a> DukValue<'a> {
     /// Return the value as a string.
     pub fn as_str(&self) -> Option<String> {
         match self {
             DukValue::Undefined => Some(String::from("undefined")),
             DukValue::Null => Some(String::from("null")),
-            DukValue::Number(ref n) => Some(String::from(n.as_str())),
+            DukValue::Number(n) => Some(String::from(n.as_str())),
             DukValue::Boolean(b) => Some(b.to_string()),
             DukValue::String(s) => Some(s.clone()),
-            DukValue::Object(ref _o) => _o.clone().encode()
+            DukValue::Object(o) => o.encode(),
         }
     }
+
     /// Return the value as a duk_bool_t (u32).
     pub fn as_duk_bool(&self) -> Option<duk_bool_t> {
         match self {
@@ -241,66 +277,72 @@ impl DukValue {
                 } else {
                     Some(0)
                 }
-            },
-            _ => None
+            }
+            _ => None,
         }
     }
+
     /// Return the value as a bool.
     pub fn as_bool(&self) -> Option<bool> {
         match self {
             DukValue::Boolean(b) => Some(*b),
-            _ => None
+            _ => None,
         }
     }
+
     /// Return the value as a DukNumber.
     pub fn as_number(&self) -> Option<DukNumber> {
         match self {
             DukValue::Number(ref n) => Some(n.clone()),
-            _ => None
+            _ => None,
         }
     }
+
     /// Return the value as a DukObject.
-    pub fn as_object(&mut self) -> Option<&mut DukObject> {
+    pub fn as_object(&self) -> Option<&'a DukObject> {
         match self {
-            DukValue::Object(ref mut o) => {
-                Some(o)
-            },
-            _ => None
+            DukValue::Object(o) => Some(o),
+            _ => None,
         }
     }
+
     /// Return the value as an f64.
     pub fn as_f64(&self) -> Option<f64> {
         match self {
             DukValue::Number(ref n) => Some(n.as_f64()),
-            _ => None
+            _ => None,
         }
     }
+
     /// Check if this value is an f64.
     pub fn is_f64(&self) -> bool {
         match self {
             DukValue::Number(ref n) => n.is_f64(),
-            _ => false
+            _ => false,
         }
     }
+
     /// Check if this value is an i64.
     pub fn is_i64(&self) -> bool {
         match self {
             DukValue::Number(ref n) => n.is_i64(),
-            _ => false
+            _ => false,
         }
     }
+
     /// Check if this value is a bool.
     pub fn is_bool(&self) -> bool {
         match self {
             DukValue::Boolean(_b) => true,
-            _ => false
+            _ => false,
         }
     }
+
     /// Return the value as an i64.
     pub fn as_i64(&self) -> Option<i64> {
         match self {
             DukValue::Number(ref n) => Some(n.as_i64()),
-            _ => None
+            _ => None,
         }
     }
 }
@@ -315,21 +357,30 @@ pub struct DukError {
     /// Errors have some sort of internal structure, but the duktape
     /// documentation always just converts them to strings.  So that's all
     /// we'll store for now.
-    message: Option<String>
+    message: Option<String>,
 }
 
 impl DukError {
     /// Create a DukError from an error code (no message).
     pub fn from_code(code: DukErrorCode) -> DukError {
-        DukError{code: code, message: None}
+        DukError {
+            code: code,
+            message: None,
+        }
     }
     /// Create a DukError from an error message (no code).
     pub fn from_str(message: &str) -> DukError {
-        DukError{code: DukErrorCode::Error, message: Some(message.to_string())}
+        DukError {
+            code: DukErrorCode::Error,
+            message: Some(message.to_string()),
+        }
     }
     /// Create a DukError from a code and message.
     pub fn from(code: DukErrorCode, message: &str) -> DukError {
-        DukError{code: code, message: Some(message.to_string())}
+        DukError {
+            code: code,
+            message: Some(message.to_string()),
+        }
     }
     /// Return the message stored in the DukError (or None if there isn't one).
     pub fn to_string(&self) -> Option<String> {
@@ -337,19 +388,14 @@ impl DukError {
     }
 }
 
-impl Error for DukError {
-    fn description(&self) -> &str { "script error:" }
-
-    fn cause(&self) -> Option<&Error> { None }
-}
+impl Error for DukError {}
 
 impl fmt::Display for DukError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match (&self.message, self.code) {
             (&Some(ref msg), _) => write!(f, "{}", msg),
             (&None, DukErrorCode::Error) => write!(f, "an unknown error occurred"),
-            (&None, code) => 
-                write!(f, "type: {:?} code: {:?}", code, code as duk_int_t)
+            (&None, code) => write!(f, "type: {:?} code: {:?}", code, code as duk_int_t),
         }
     }
 }
@@ -359,95 +405,106 @@ pub type DukResult<T> = std::result::Result<T, DukError>;
 /// Wrapper around a duktape context. Usable for evaluating and returning values from the context that can be used in Rust.
 #[derive(Clone, Debug)]
 pub struct DukContext {
-    pub ctx: Option<*mut duk_context>,
+    ctx: NonNull<duk_context>,
+}
+
+impl Drop for DukContext {
+    fn drop(&mut self) {
+        let raw_ctx = self.ctx.as_ptr();
+        unsafe {
+            duk_destroy_heap(raw_ctx);
+        }
+    }
 }
 
 impl DukContext {
     /// Create a duktape context.
-    pub fn new() -> DukContext {
-        unsafe {
-            DukContext { ctx: Some(duk_create_heap_default()) }
-        }
-    }
-    /// Destroy the duktape context's heap. Should not be used after calling this.
-    pub fn destroy(self) {
-        unsafe {
-            duk_destroy_heap(self.ctx.expect("Invalid context pointer."));
+    pub fn new() -> anyhow::Result<DukContext> {
+        let ctx = unsafe { NonNull::new(duk_create_heap_default()) };
+        match ctx {
+            Some(ctx) => Ok(Self { ctx }),
+            None => Err(anyhow::anyhow!("Could not create context")),
         }
     }
+
     /// Decode a JSON string into the context, returning a DukObject.
     pub fn decode_json(&mut self, json: &str) -> DukValue {
-        match self.ctx {
-            Some(ctx) => {
-                unsafe {
-                    duk_push_lstring(ctx, json.as_ptr() as *const i8, json.len() as duk_size_t);
-                    duk_json_decode(ctx, -1);
-                    self.get_value()
-                }
-            },
-            None => DukValue::Undefined
-        }
-    }
-    /// Get a DukValue from the value at the top of the value stack in the context.
-    pub fn get_value(&mut self) -> DukValue {
         unsafe {
-            let t = duk_get_type(self.ctx.expect("Invalid context pointer"), -1);
-            match t as u32 {
-                DUK_TYPE_NONE => DukValue::Null,
-                DUK_TYPE_UNDEFINED => DukValue::Undefined,
-                DUK_TYPE_NULL => DukValue::Null,
-                DUK_TYPE_BOOLEAN => DukValue::Boolean(duk_get_boolean(self.ctx.expect("Invalid context pointer"), -1) == 1),
-                DUK_TYPE_NUMBER => {
-                    let v = duk_get_number(self.ctx.expect("Invalid context pointer"), -1);
-                    if v.fract() > 0_f64 {
-                        DukValue::Number(DukNumber::Float(v))
-                    } else {
-                        if v.is_nan() {
-                            DukValue::Number(DukNumber::NaN)
-                        } else if v.is_infinite() {
-                            DukValue::Number(DukNumber::Infinity)
-                        } else {
-                            DukValue::Number(DukNumber::Int(v as i64))
-                        }
-                    }
-                },
-                DUK_TYPE_STRING => {
-                    use std::ffi::CStr;
-                    let v = duk_get_string(self.ctx.expect("Invalid context pointer"), -1);
-                    let t = CStr::from_ptr(v);
-                    let cow = t.to_string_lossy();
-                    DukValue::String(String::from(cow))
-                },
-                DUK_TYPE_OBJECT => {
-                    let obj = DukObject::new(self.clone());
-                    DukValue::Object(obj)
-                },
-                _ => DukValue::Undefined
+            duk_push_lstring(
+                self.ctx.as_ptr(),
+                json.as_ptr() as *const i8,
+                json.len() as duk_size_t,
+            );
+            duk_json_decode(self.ctx.as_ptr(), -1);
+        }
+        self.get_value()
+    }
+
+    /// Get a DukValue from the value at the top of the value stack in the context.
+    pub fn get_value(&self) -> DukValue {
+        let r#type = unsafe { duk_get_type(self.ctx.as_ptr(), -1) as u32 };
+        match r#type {
+            DUK_TYPE_NONE => DukValue::Null,
+            DUK_TYPE_UNDEFINED => DukValue::Undefined,
+            DUK_TYPE_NULL => DukValue::Null,
+            DUK_TYPE_BOOLEAN => {
+                let val = unsafe { duk_get_boolean(self.ctx.as_ptr(), -1) };
+                DukValue::Boolean(val == 1)
             }
+            DUK_TYPE_NUMBER => {
+                let v = unsafe { duk_get_number(self.ctx.as_ptr(), -1) };
+                if v.fract() > 0_f64 {
+                    DukValue::Number(DukNumber::Float(v))
+                } else {
+                    if v.is_nan() {
+                        DukValue::Number(DukNumber::NaN)
+                    } else if v.is_infinite() {
+                        DukValue::Number(DukNumber::Infinity)
+                    } else {
+                        DukValue::Number(DukNumber::Int(v as i64))
+                    }
+                }
+            }
+            DUK_TYPE_STRING => {
+                let v = unsafe {
+                    let v = duk_get_string(self.ctx.as_ptr(), -1);
+                    CStr::from_ptr(v)
+                };
+                let cow = v.to_string_lossy();
+                DukValue::String(String::from(cow))
+            }
+            DUK_TYPE_OBJECT => {
+                let obj = DukObject::new(self);
+                DukValue::Object(obj)
+            }
+            _ => DukValue::Undefined,
         }
     }
     /// Evaluate a string, returning the resulting value.
-    pub fn eval_string(&mut self, code: &str) -> DukResult<DukValue> {
+    pub fn eval_string(&self, code: &str) -> DukResult<DukValue> {
         unsafe {
-            if duk_eval_string(self.ctx.expect("Invalid context pointer"), code) == 0 {
+            if duk_eval_string(self.ctx.as_ptr(), code) == 0 {
                 let result = self.get_value();
-                duk_pop_2(self.ctx.expect("Invalid context pointer"));
+                duk_pop_2(self.ctx.as_ptr());
                 Ok(result)
             } else {
-                let code = duk_get_error_code(self.ctx.expect("Invalid context pointer"), -1) as u32;
+                let code = duk_get_error_code(self.ctx.as_ptr(), -1) as u32;
                 let name = "stack";
-                duk_get_prop_lstring(self.ctx.expect("Invalid context pointer"), -1, name.as_ptr() as *const i8, name.len() as duk_size_t);
+                duk_get_prop_lstring(
+                    self.ctx.as_ptr(),
+                    -1,
+                    name.as_ptr() as *const i8,
+                    name.len() as duk_size_t,
+                );
                 let val = self.get_value();
-                duk_pop(self.ctx.expect("Invalid context pointer"));
+                duk_pop(self.ctx.as_ptr());
                 match val.as_str() {
                     Some(v) => {
                         use std::mem;
                         let c: DukErrorCode = mem::transmute(code);
                         Err(DukError::from(c, v.as_ref()))
-                    },
-                    None => {
-                        Err(DukError::from_code(DukErrorCode::Error))
                     }
+                    None => Err(DukError::from_code(DukErrorCode::Error)),
                 }
             }
         }
@@ -457,21 +514,59 @@ impl DukContext {
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn test_create_context() {
+        let ctx = DukContext::new();
+        assert!(ctx.is_ok());
+    }
+
+    #[test]
+    fn test_eval_to_number() {
+        let ctx = DukContext::new().unwrap();
+        let val = ctx.eval_string("10+5").unwrap();
+        let val = val.as_number().unwrap();
+        assert_eq!(val, DukNumber::Int(15));
+    }
+
+    #[test]
+    fn test_eval_to_string() {
+        let ctx = DukContext::new().unwrap();
+        let val = ctx.eval_string("'something'.toUpperCase()").unwrap();
+        let val = val.as_str().unwrap();
+        assert_eq!(val, String::from("SOMETHING"));
+    }
+
+    #[test]
+    fn test_eval_to_object() {
+        let ctx = DukContext::new().unwrap();
+        let val = ctx.eval_string("({\"some\":\"thing\"})").unwrap();
+        let _ = val.as_object().unwrap();
+    }
+
+    #[test]
+    fn test_get_prop_from_object() {
+        let ctx = DukContext::new().unwrap();
+        let val = ctx.eval_string("({\"some\":\"thing\"})").unwrap();
+        let obj = val.as_object().unwrap();
+        assert_eq!(
+            obj.get_prop("some").unwrap().as_str().unwrap(),
+            String::from("thing")
+        );
+    }
+
     #[test]
     fn test_eval_ret() {
         // Create a new context
-	    let mut ctx = DukContext::new();
+        let mut ctx = DukContext::new().unwrap();
         // Obtain array value from eval
-	    let mut val = ctx.eval_string("([1,2,3])").unwrap();
+        let mut val = ctx.eval_string("([1,2,3])").unwrap();
         // Get the array as an object
-	    let obj = val.as_object().expect("WAS NOT AN OBJECT");
+        let obj = val.as_object().expect("WAS NOT AN OBJECT");
         // Set index 3 as 4
-        obj.set_prop("3", DukValue::Number(DukNumber::Int(4))).unwrap();
+        obj.set_prop("3", DukValue::Number(DukNumber::Int(4)))
+            .unwrap();
         // Encode the object to json and validate it is correct
         assert_eq!("[1,2,3,4]", obj.encode().expect("Should be a string"));
-        // Free the object for garbage collection
-        obj.free();
-        // Destroy the heap to free the memory
-        ctx.destroy();
     }
 }