path: root/src/tools/gftest/README.md

# gftest: Automatic systematic test case generation for GF grammars

`gftest` is a program for automatically generating systematic test
cases for GF grammars. The basic use case is to give `gftest` a
PGF grammar, a concrete language and a function; then `gftest` generates a
representative and minimal set of example sentences for a human to look at.

There are examples of actual generated test cases later in this
document, as well as the full list of options to give to `gftest`.

## Table of Contents

- [Installation](#installation)
  - [Prerequisites](#prerequisites)
  - [Install gftest](#install-gftest)
- [Common use cases](#common-use-cases)
  - [Grammar: `-g`](#grammar--g)
  - [Language: `-l`](#language--l)
  - [Function(s) to test: `-f`](#functions-to-test--f)
  - [Start category for context: `-s`](#start-category-for-context--s)
  - [Category to test: `-c`](#category-to-test--c)
  - [Tree to test: `-t`](#tree-to-test--t)
  - [Compare against an old version of the grammar: `-o`](#compare-against-an-old-version-of-the-grammar--o)
  - [Information about a particular string: `--concr-string`](#information-about-a-particular-string---concr-string)
  - [Write into a file: `-w`](#write-into-a-file--w)
- [Less common use cases](#less-common-use-cases)
  - [Empty or always identical fields: `-e`, `-q`](#empty-or-always-identical-fields--e--q)
  - [Unused fields: `-u`](#unused-fields--u)
  - [Erased trees: `-r`](#erased-trees--r)
  - [--show-coercions](#--show-coercions)
  - [--count-trees](#--count-trees)


## Installation

### Prerequisites

You need the library `PGF2`. Here are instructions how to install:

1) Install C runtime: go to the directory [GF/src/runtime/c](https://github.com/GrammaticalFramework/GF/tree/master/src/runtime/c), see
instructions in INSTALL
1) Install PGF2 in one of the two ways:
  * **EITHER** Go to the directory
   [GF/src/runtime/haskell-bind](https://github.com/GrammaticalFramework/GF/tree/master/src/runtime/haskell-bind),
   do `cabal install`
  * **OR**  Go to the root directory of
    [GF](https://github.com/GrammaticalFramework/GF/) and compile GF
    with C-runtime system support: `cabal
    install -fc-runtime`, see more information [here](http://www.grammaticalframework.org/doc/gf-developers.html#toc16).

### Install gftest

Go to
[GF/src/tools](https://github.com/GrammaticalFramework/GF/tree/master/src/tools),
do `cabal install`. It creates an executable `gftest`.


## Common use cases

Run `gftest --help` of `gftest -?` to get the list of options.

```
Common flags:
  -g --grammar=FILE        Path to the grammar (PGF) you want to test
  -l --lang="Eng Swe"      Concrete syntax + optional translations
  -f --function=UseN       Test the given function(s)
  -c --category=NP         Test all functions with given goal category
  -t --tree="UseN tree_N"  Test the given tree
  -s --start-cat=Utt       Use the given category as start category
     --show-cats           Show all available categories
     --show-funs           Show all available functions
     --funs-of-arity=2     Show all functions of arity 2
     --show-coercions      Show coercions in the grammar
     --concr-string=the    Show all functions that include given string
  -q --equal-fields        Show fields whose strings are always identical
  -e --empty-fields        Show fields whose strings are always empty
  -u --unused-fields       Show fields that never make it into the top category
  -r --erased-trees        Show trees that are erased
  -o --old-grammar=ITEM    Path to an earlier version of the grammar
     --only-changed-cats   When comparing against an earlier version of a
                           grammar, only test functions in categories that have
                           changed between versions
  -b --treebank=ITEM       Path to a treebank
     --count-trees=3       Number of trees of depth <depth>
  -d --debug               Show debug output
  -w --write-to-file       Write the results in a file (<GRAMMAR>_<FUN>.org)
  -? --help                Display help message
  -V --version             Print version information
```

### Grammar: `-g`

Give the PGF grammar as an argument with `-g`. If the file is not in
the same directory, you need to give the full file path.

You can give the grammar with or without `.pgf`. 

Without a concrete syntax you can't do much, but you can see the
available categories and functions with `--show-cats` and `--show-funs`

Examples:

* `gftest -g Foods --show-funs`
* `gftest -g /home/inari/grammars/LangEng.pgf --show-cats`


### Language: `-l`

Give a concrete language. It assumes the format `AbsNameConcName`, and you should only give the `ConcName` part.

You can give multiple languages, in which case it will create the test cases based on the first, and show translations in the rest.

Examples:

* `gftest -g Phrasebook -l Swe --show-cats`  
* `gftest -g Foods -l "Spa Eng" -f Pizza`

### Function(s) to test: `-f` 

Given a grammar (`-g`) and a concrete language ( `-l`), test a function or several functions. 

Examples:

* `gftest -g Lang -l "Dut Eng" -f UseN`
* `gftest -g Phrasebook -l Spa -f "ByTransp ByFoot"`

You can use the wildcard `*`, if you want to match multiple functions. Examples:

* `gftest -g Lang -l Eng -f "*hat*"`  

matches `hat_N, hate_V2, that_Quant, that_Subj, whatPl_IP` and `whatSg_IP`.

* `gftest -g Lang -l Eng -f "*hat*u*"`  

matches `that_Quant` and `that_Subj`.

* `gftest -g Lang -l Eng -f "*"`  

matches all functions in the grammar. (As of March 2018, takes 13
minutes for the English resource grammar, and results in ~40k
lines. You may not want to do this for big grammars.)

### Start category for context: `-s`

Give a start category for contexts. Used in conjunction with `-f`,
`-c`, `-t` or `--count-trees`. If not specified, contexts are created
for the start category of the grammar. 

Example:

* `gftest -g Lang -l "Dut Eng" -f UseN -s Adv`

This creates a hole of `CN` in `Adv`, instead of the default start category.

### Category to test: `-c`

Given a grammar (`-g`) and a concrete language ( `-l`), test all functions that return a given category.

Examples:

* `gftest -g Phrasebook -l Fre -c Modality`
* `gftest -g Phrasebook -l Fre -c ByTransport -s Action`


### Tree to test: `-t`

Given a grammar (`-g`) and a concrete language ( `-l`), test a complete tree.

Example:

* `gftest -g Phrasebook -l Dut -t "ByTransp Bus"`

You can combine it with any of the other flags, e.g. put it in a
different start category:

* `gftest -g Phrasebook -l Dut -t "ByTransp Bus" -s Action`


This may be useful for the following case. Say you tested `PrepNP`,
and the default NP it gave you only uses the word *car*, but you
would really want to see it for some other noun—maybe `car_N` itself
is buggy, and you want to be sure that `PrepNP` works properly. So
then you can call the following:

* `gftest -g TestLang -l Eng -t "PrepNP with_Prep (MassNP (UseN beer_N))"`

### Compare against an old version of the grammar: `-o`

Give a grammar, a concrete syntax, and an old version of the same
grammar as a separate PGF file. The program generates test sentences
for all functions, linearises with both grammars, and outputs those
that differ between the versions. It writes the differences into files.

Example:

```
> gftest -g TestLang -l Eng -o TestLangOld 
Created file TestLangEng-ccat-diff.org
Testing functions in… 
<categories flashing by>
Created file TestLangEng-lin-diff.org
Created files TestLangEng-(old|new)-funs.org
```

* TestLangEng-ccat-diff.org: All concrete categories that have
  changed. Shows e.g. if you added or removed a parameter or a
  field.

* TestLangEng-lin-diff.org: All trees that have different
linearisations in the following format. **This is usually the most
relevant file.**
```
* send_V3

** UseCl (TTAnt TPres ASimul) PPos (PredVP (UsePron we_Pron) (ReflVP (Slash3V3 ∅ (UsePron it_Pron))))
TestLangDut> we sturen onszelf ernaar
TestLangDut-OLD> we sturen zichzelf ernaar


** UseCl (TTAnt TPast ASimul) PPos (PredVP (UsePron we_Pron) (ReflVP (Slash3V3 ∅ (UsePron it_Pron))))
TestLangDut> we stuurden onszelf ernaar
TestLangDut-OLD> we stuurden zichzelf ernaar
```

* TestLangEng-old-funs.org and TestLangEng-new-funs.org: groups the
  functions by their concrete categories. Shows difference if you have
  e.g. added or removed parameters, and that has created new versions of
  some functions: say you didn't have gender in nouns, but now you
  have, then all functions taking nouns have suddenly a gendered
  version. **This is kind of hard to read, don't worry too much if the
  output doesn't make any sense.** 

You can give an additional parameter, `--only-changed-cats`, if you
only want to test functions in those categories that you have changed,
like this: `gftest -g TestLang -l Eng -o TestLangOld
--only-changed-cats`. This makes it run faster.

### Information about a particular string: `--concr-string`

Show all functions where the given concrete string appears as syncategorematic string (i.e. not from the arguments).

Example:

* `gftest -l Eng --concr-string it`

which gives the answer `==> CleftAdv, CleftNP, DefArt, ImpersCl, it_Pron`


### Write into a file: `-w`

Writes the results into a file of format `<GRAMMAR>_<FUN or CAT>.org`,
e.g. TestLangEng-UseN.org. Recommended to open it in emacs org-mode,
so you get an overview, and you can maybe ignore some trees if you
think they are redundant. 

1) When you open the file, you see a list of generated test cases, like this: ![Instructions how to use org mode](https://raw.githubusercontent.com/inariksit/GF-testing/master/doc/instruction-1.png)  
Place cursor to the left and click tab to open it.

2) You get a list of contexts for the test case. Keep the cursor where it was if you want to open everything at the same time. Alternatively, scroll down to one of the contexts and press tab there, if you only want to open one.
![Instructions how to use org mode](https://raw.githubusercontent.com/inariksit/GF-testing/master/doc/instruction-2.png)

3) Now you can read the linearisations.  
![Instructions how to use org mode](https://raw.githubusercontent.com/inariksit/GF-testing/master/doc/instruction-3.png)

If you want to close the test case, just press tab again, keeping the
cursor where it's been all the time (line 31 in the pictures).

## Less common use cases

The topics here require some more obscure GF-fu. No need to worry if
the terms are not familiar to you.


### Empty or always identical fields: `-e`, `-q`

Information about the fields: always empty, or always equal to each
other. Example of empty fields:

```
> gftest -g Lang -l Dut -e
* Empty fields:
==> Ant: s

==> Pol: s

==> Temp: s

==> Tense: s

==> V: particle, prefix
```

The categories `Ant`, `Pol`, `Temp` and `Tense` are as expected empty;
there's no string to be added to the sentences, just a parameter that
*chooses* the right forms of the clause.

`V` having empty fields `particle` and `prefix` is in this case just
an artefact of a small lexicon: we happen to have no intransitive
verbs with a particle or prefix in the core 300-word vocabulary. But a
grammarian would know that it's still relevant to keep those fields,
because in some bigger application such a verb may show up.

On the other hand, if some other field is always empty, it might be a
hint for the grammarian to remove it altogether.

Example of equal fields:

```
> gftest -g Lang -l Dut -q
* Equal fields:
==> RCl:
s Pres Simul Pos Utr Pl
s Pres Simul Pos Neutr Pl

==> RCl:
s Pres Simul Neg Utr Pl
s Pres Simul Neg Neutr Pl

==> RCl:
s Pres Anter Pos Utr Pl
s Pres Anter Pos Neutr Pl

==> RCl:
s Pres Anter Neg Utr Pl
s Pres Anter Neg Neutr Pl

==> RCl:
s Past Simul Pos Utr Pl
s Past Simul Pos Neutr Pl
…
```

Here we can see that in relative clauses, gender does not seem to play
any role in plural. This could be a hint for the grammarian to make a
leaner parameter type, e.g. `param RClAgr = SgAgr <everything incl. gender> | PlAgr <no gender here>`.


### Unused fields: `-u`

These fields are not empty, but they are never used in the top
category. The top category can be specified by `-s`, otherwise it is
the default start category of the grammar. 

Note that if you give a start category from very low, such as `Adv`,
you get a whole lot of categories and fields that naturally have no
way of ever making it into an adverb. So this is mostly meaningful to
use for the start category.


### Erased trees: `-r`

Show trees that are erased in some function, i.e. a function `F : A -> B -> C` has arguments A and B, but doesn't use one of them in the resulting tree of type C. This is usually a bug.

Example:

`gftest -g Lang -l "Dut Eng" -r`  

output:
```
* Erased trees:

** RelCl (ExistNP something_NP) : RCl
- Tree:  AdvS (PrepNP with_Prep (RelNP (UsePron it_Pron) (UseRCl (TTAnt TPres ASimul) PPos (RelCl (ExistNP something_NP))))) (UseCl (TTAnt TPres ASimul) PPos (ExistNP something_NP))
- Lin:   ermee is er iets
- Trans: with it, such that there is something, there is something

** write_V2 : V2
- Tree:  AdvS (PrepNP with_Prep (PPartNP (UsePron it_Pron) write_V2)) (UseCl (TTAnt TPres ASimul) PPos (ExistNP something_NP))
- Lin:   ermee is er iets
- Trans: with it written there is something
```

In the first result, an argument of type `RCl` is missing in the tree constructed by `RelNP`, and in the second result, the argument `write_V2` is missing in the tree constructed by `PPartNP`. In both cases, the English linearisation contains all the arguments, but in the Dutch one they are missing. (This bug is already fixed, just showing it here to demonstrate the feature.)


### --show-coercions

First I'll explain what *coercions* are, then why it may be
interesting to show them. Let's take a Spanish Foods grammar, and
consider the category `Quality`—those `Good Pizza` and `Vegan Pizza`
that you saw in the previous section. `Good`
"bueno/buena/buenos/buenas" goes before the noun it modifies, whereas
`Vegan` "vegano/vegana/…" goes after, so these will become different
*concrete categories* in the PGF: `Quality_before` and
`Quality_after`. (In reality, they are something like `Quality_7` and
`Quality_8` though.)

Now, this difference is meaningful only when the adjective is modifying
the noun: "la buena pizza" vs. "la pizza vegana". But when the
adjective is in a predicative position, they both behave the same:
"la pizza es buena" and "la pizza es vegana". For this, the grammar
creates a *coercion*: both `Quality_before` and `Quality_after` may be
treated as `Quality_whatever`. To save some redundant work, this coercion `Quality_whatever`
appears in the type of predicative function, whereas the
modification function has to be split into two different functions,
one taking `Quality_before` and other `Quality_after`.

Now you know what coercions are, this is how it looks like in the program:

```
> gftest -g Foods -l Spa --show-coercions
* Coercions in the grammar:
Quality_7--->_11
Quality_8--->_11
```

(Just mentally replace 7 with `before`, 8 with `after` and 11 with `whatever`.)

### --count-trees

Number of trees up to given size. Gives a number how many trees, and a
couple of examples from the highest size. Examples:

```
> gftest -g TestLang -l Eng --count-trees 10
There are 675312 trees up to size 10, and 624512 of exactly size 10.
For example: 
* AdvS today_Adv (UseCl (TTAnt TPres ASimul) PPos (ExistNP (UsePron i_Pron)))
* UseCl (TTAnt TCond AAnter) PNeg (PredVP (SelfNP (UsePron they_Pron)) UseCopula)
```

This counts the number of trees in the start category. You can also
specify a category:

```
> gftest -g TestLang -l Eng --count-trees 4 -s Adv
There are 2409 trees up to size 4, and 2163 of exactly size 4.
For example: 
* AdAdv very_AdA (PositAdvAdj young_A)
* PrepNP above_Prep (UsePron they_Pron)
```

### --funs-of-arity

Show all functions of given arity (not up to).

Example:

```
> gftest -g Phrasebook --funs-of-arity 3
* Functions in the grammar of arity 3:
ADoVerbPhrasePlace
AModVerbPhrase
HowFarFromBy
QWhereModVerbPhrase
```