Testing Strategy

Relevant source files

The following files were used as context for generating this wiki page:

• package.json
• README.md
• src/index.js
• src/distance.js
• src/perpendicular-distance.js

The testing strategy for the geo-path-reducer library focuses on verifying the implementation of the Douglas-Peucker algorithm for curve simplification. The primary goal is to ensure that spatial data points are correctly reduced based on a user-defined threshold (epsilon) while maintaining the integrity of the geographic path.

Currently, the project infrastructure indicates a nascent stage for automated testing. While the configuration exists to execute tests, the current implementation lacks specific test suites, relying instead on manual verification examples provided in documentation to validate the core logic of coordinate distance calculations and recursive point reduction.

Sources: package.json:7, README.md:1-10, src/index.js:3-30

Infrastructure and Execution

The project utilizes npm as its primary package manager and task runner. The testing entry point is defined within the project configuration, though it currently serves as a placeholder.

Component	Definition	Description
Test Command	npm test	The standard command to initiate the test suite.
Current State	Error Placeholder	Currently returns Error: no test specified.
Environment	Node.js (ES Module)	The project is configured as type: module.

Sources: package.json:6-8,11

Execution Flow

The following diagram illustrates the intended flow of testing within the current package lifecycle:

The current script configuration forces a non-zero exit code, signaling that automated test coverage has not yet been implemented for the library.
Sources: package.json:7

Verification Logic

The "Testing Strategy" by extension relies on the mathematical accuracy of the underlying geographic calculations. To ensure the path reducer functions correctly, the following components require unit-level verification:

1. Distance Calculations

The core of the reduction logic depends on the distance function, which calculates the great-circle distance between two points on Earth using the Haversine formula. Testing must verify that:

• Input latitudes and longitudes are correctly converted to radians.
• The Earth's radius is treated as a constant (6371 km).
• The resulting distance (d) accurately reflects the spatial separation.

Sources: src/distance.js:1-16

2. Perpendicular Thresholds

The perpendicular-distance.js module calculates the distance from a point to a line segment defined by two other points. This is critical for the Douglas-Peucker algorithm's decision-making process.

Testing this module involves verifying the calculation of the semi-perimeter s and the subsequent area-based distance formula.
Sources: src/perpendicular-distance.js:3-12

Manual Validation and API Usage

In the absence of automated test suites, the project provides a usage example in the README.md that serves as a functional test case. This example provides a set of coordinates and an epsilon value to verify the output of the geoPathReducer.

Parameter	Type	Expected Data Structure
points	Array	[{ lat: Number, lng: Number }, ...]
epsilon	Number	Maximum distance in degrees (e.g., 0.0001)

Sources: README.md:15-32, src/index.js:3-5

Recursive Logic Verification

The path reducer uses a recursive strategy. A comprehensive test suite should cover:

1. Base Case: If no point's distance exceeds epsilon, return only the start and end points.
2. Recursive Case: If a point exceeds epsilon, split the array at that point and recurse on both halves.

// Verification of recursion logic in src/index.js
if (dmax > epsilon) {
    const leftPoints = points.slice(0, index + 1);
    const rightPoints = points.slice(index);
    const simplifiedLeft = douglasPeucker(leftPoints, epsilon);
    const simplifiedRight = douglasPeucker(rightPoints, epsilon);
    return simplifiedLeft.slice(0, simplifiedLeft.length - 1).concat(simplifiedRight);
}

Note: The implementation in src/index.js references douglasPeucker recursively, though the function is exported as geoPathReducer.
Sources: src/index.js:17-25

Summary

The current testing strategy for geo-path-reducer is primarily manual, centered around provided implementation examples and the core mathematical functions in the src/ directory. While the package.json provides a hook for automated testing, the focus remains on the accuracy of the Haversine distance calculations and the recursive Douglas-Peucker implementation to simplify geographic paths.

Sources: package.json:7, src/index.js:3-30, src/distance.js:1-16