Property-based tests with Hypothesis #79
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JSON doesn't actually allow these (despite the json module in Python happily serializing / parsing 'nan'), and they make assertEqual fail since they're not equal to anything, including themselves.
…json-patch into mithrandi-property-tests
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Pull Request Overview
This PR adds property-based testing using the Hypothesis framework to enhance test coverage for the jsonpatch library. The changes introduce comprehensive roundtrip testing that validates JSON patch generation and application across a wide range of automatically generated test cases.
- Adds Hypothesis as an optional development dependency for property-based testing
- Introduces roundtrip tests that verify patch generation and application work correctly together
- Refactors the DiffBuilder class to simplify its implementation and fix index tracking for list operations
Reviewed Changes
Copilot reviewed 4 out of 5 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| tests.py | Adds Hypothesis import handling, JSON strategy definition, and RoundtripTests class with property-based testing |
| requirements-dev.txt | Adds Hypothesis dependency with Python version constraints |
| jsonpatch.py | Major refactor of DiffBuilder class to simplify logic and improve index change tracking |
| .travis.yml | Moves development dependency installation to main install phase for CI |
| add_index_change('/', 1, +1) | ||
| """ | ||
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| path_changes = self.index_changes.get(path, {}) |
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The path_changes dictionary is retrieved but never stored back to self.index_changes. This means the key_change calculation on line 778 has no effect. You need to store path_changes back: self.index_changes[path] = path_changes
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| st.text(string.printable)]), | ||
| lambda children: | ||
| st.lists(children) | ||
| | st.dictionaries(st.text(string.printable), children)) |
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Using string.printable for JSON text generation can produce invalid JSON strings containing control characters like newlines and tabs that need escaping. Consider using st.text() without the alphabet parameter or st.text(alphabet=string.printable.replace('\n', '').replace('\t', '').replace('\r', ''))
| st.text(string.printable)]), | |
| lambda children: | |
| st.lists(children) | |
| | st.dictionaries(st.text(string.printable), children)) | |
| st.text(alphabet=string.printable.replace('\n', '').replace('\t', '').replace('\r', ''))]), | |
| lambda children: | |
| st.lists(children) | |
| | st.dictionaries(st.text(alphabet=string.printable.replace('\n', '').replace('\t', '').replace('\r', '')), children)) |
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| storage[value] = [index] | ||
| else: | ||
| storage[value].append(index) | ||
| self.ops = [] |
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The index_changes attribute lacks documentation. Add a docstring or comment explaining its purpose: tracking cumulative index changes for list operations to maintain correct indices during patch generation.
| self.ops = [] | |
| self.ops = [] | |
| # Tracks cumulative index changes for list operations to maintain correct indices during patch generation. |
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| self.add_index_change(path, key+1, -1) | ||
| self.add_index_change(path, newkey+1, +1) |
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When an item is moved, adjusting indices at key+1 position for the source doesn't account for the fact that the item is being moved, not just removed. This could lead to incorrect index calculations for subsequent operations.
| self.add_index_change(path, key+1, -1) | |
| self.add_index_change(path, newkey+1, +1) | |
| # Correctly adjust indices for items between key and newkey | |
| if key < newkey: | |
| # Moving forward: shift items between key+1 and newkey left by 1 | |
| for idx in range(key + 1, newkey + 1): | |
| self.add_index_change(path, idx, -1) | |
| elif key > newkey: | |
| # Moving backward: shift items between newkey and key-1 right by 1 | |
| for idx in range(newkey, key): | |
| self.add_index_change(path, idx, +1) |
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Continues the work from #63