Make assert_object_equals more accurate and give better error messages

[johnmellor]

As an alternative to #143, this pull request proposes to fix assert_object_equals.

Consider the following tests:

test(function() {
    assert_object_equals(false, true);
}, "1");
test(function() {
    assert_object_equals(1, true);
}, "2");
test(function() {
    assert_object_equals(false, {});
}, "3");
test(function() {
    assert_object_equals({}, false);
}, "4");
test(function() {
    assert_object_equals("abc", ["a", "b", "c"]);
}, "5");
test(function() {
    assert_object_equals(["a", "b", "c"], "abc");
}, "6");
test(function() {
    assert_object_equals({a:{}}, {a:false});
}, "7");
test(function() {
    assert_object_equals({b:{}}, {b:null});
}, "8");
test(function() {
    assert_object_equals({c:null}, {c:{}});
}, "9");
test(function() {
    assert_object_equals({d:false}, {d:{}});
}, "10");
test(function() {
    assert_object_equals({x:{y:{z:false}}}, {x:{y:{z:true}}});
}, "11");

Previously, the first 8 would incorrectly pass, and the last 3 would
give confusing error messages:

FAIL 9 assert_object_equals: property "c" expected object "[object Object]" got object "[object Object]"
FAIL 10 assert_object_equals: property "d" expected object "[object Object]" got object "[object Object]"
FAIL 11 assert_object_equals: property "z" expected object "[object Object]" got object "[object Object]"

After this patch, all the cases fail correctly and have clear error messages:

FAIL 1 assert_object_equals: expected true but got false
FAIL 2 assert_object_equals: expected (boolean) true but got (number) 1
FAIL 3 assert_object_equals: expected (object) object "[object Object]" but got (boolean) false
FAIL 4 assert_object_equals: expected (boolean) false but got (object) object "[object Object]"
FAIL 5 assert_object_equals: expected (object) ["a", "b", "c"] but got (string) "abc"
FAIL 6 assert_object_equals: expected (string) "abc" but got (object) ["a", "b", "c"]
FAIL 7 assert_object_equals: property ["a"]: expected (boolean) false but got (object) object "[object Object]"
FAIL 8 assert_object_equals: property ["b"]: expected null but got object "[object Object]"
FAIL 9 assert_object_equals: property ["c"]: expected object "[object Object]" but got null
FAIL 10 assert_object_equals: property ["d"]: expected (object) object "[object Object]" but got (boolean) false
FAIL 11 assert_object_equals: property ["x"]["y"]["z"]: expected true but got false

[hoppipolla-critic-bot]

Critic review: https://critic.hoppipolla.co.uk/r/5759

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[jgraham]

Thank you for the patch, but I really really just want this to die. It's too complex to be good for testing.