[libcamera-devel] [RFC PATCH v2 05/14] test: yaml-parser: Test dictionary items ordering

[Laurent Pinchart]

Hi Paul,

On Mon, Jun 13, 2022 at 01:22:19PM +0900, paul.elder at ideasonboard.com wrote:
> Hi Laurent,
> 
> On Sat, Jun 04, 2022 at 09:59:30PM +0300, Laurent Pinchart via libcamera-devel wrote:
> > The order of items in a YAML dictionary may matter. Update the test to
> > ensure that it is preserved. The test currently fails at the YamlParser
> 
> My understanding is that YAML mappings are unordered [1] [2], and if
> order in the mapping is significant, then either a sequence of mappings
> [3] or flow mapping adjacent values [4] should be used.

That's a very good point. [5] even mentions

"while imposing a order on mapping keys is necessary for flattening YAML
representations to a sequential access medium, this serialization detail
must not be used to convey application level information."

The same applies to JSON ([6]).

Fixing this would require changing the syntax of the tuning files. It's
inconvenient, but not doing so opens the door to more issues in the
future :-S

> [1] https://yaml.org/spec/1.2.2/#mapping
> [2] https://yaml.org/spec/1.2.2/#3221-mapping-key-order
> [3] https://yaml.org/spec/1.2.2/#example-ordered-mappings
> [4] https://yaml.org/spec/1.2.2/#example-flow-mapping-adjacent-values

[5] https://yaml.org/spec/1.2.2/#32-information-models
[6] https://www.json.org/json-en.html

> > doesn't correctly preserve the order, this will be fixed by the next
> > commit.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  test/yaml-parser.cpp | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > diff --git a/test/yaml-parser.cpp b/test/yaml-parser.cpp
> > index 5ff4c3236dbf..582c9caed836 100644
> > --- a/test/yaml-parser.cpp
> > +++ b/test/yaml-parser.cpp
> > @@ -29,8 +29,8 @@ static const string testYaml =
> >  	"  - Mary\n"
> >  	"dictionary:\n"
> >  	"  a: 1\n"
> > -	"  b: 2\n"
> >  	"  c: 3\n"
> > +	"  b: 2\n"
> >  	"level1:\n"
> >  	"  level2:\n"
> >  	"    - [1, 2]\n"
> > @@ -428,7 +428,6 @@ protected:
> >  		}
> >  
> >  		auto memeberNames = dictObj.memberNames();
> > -		sort(memeberNames.begin(), memeberNames.end());
> >  
> >  		if (memeberNames.size() != 3) {
> >  			cerr << "Dictionary object fail to extra member names" << std::endl;
> > @@ -436,8 +435,8 @@ protected:
> >  		}
> >  
> >  		if (memeberNames[0] != "a" ||
> > -		    memeberNames[1] != "b" ||
> > -		    memeberNames[2] != "c") {
> > +		    memeberNames[1] != "c" ||
> > +		    memeberNames[2] != "b") {
> >  			cerr << "Dictionary object fail to parse member names" << std::endl;
> >  			return TestFail;
> >  		}

-- 
Regards,

Laurent Pinchart