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Testing Coordinate System Conversions in AndroidUtilCode

This test suite validates coordinate system conversions in the AndroidUtilCode library, focusing on transformations between WGS84, GCJ02, and BD09 coordinate systems. The tests verify accurate coordinate mappings using real-world locations like Tiananmen Square and New York City as reference points.

Test Coverage Overview

The test suite provides comprehensive coverage of coordinate system conversions:

Bi-directional conversions between WGS84, GCJ02, and BD09 systems
Validation using known reference coordinates from Tiananmen Square
Distance calculation verification with tolerance checks
Edge case handling for coordinate boundary conditions

Implementation Analysis

The testing approach employs JUnit 4 framework with systematic validation of coordinate transformations. Each test method follows a consistent pattern of conversion and distance-based verification, utilizing Assert statements to ensure conversion accuracy within 10-meter tolerance.

The implementation includes precise mathematical calculations using PI constants and trigonometric functions for distance measurements.

Technical Details

Testing infrastructure includes:

JUnit 4 testing framework
Custom distance calculation method using haversine formula
Static test data for known coordinate points
Tolerance-based assertion checks
Earth radius constant of 6371000 meters

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Clear test method naming reflecting functionality
Isolated test cases for each conversion type
Consistent assertion patterns
Real-world test data usage
Proper tolerance handling for floating-point comparisons

blankj/androidutilcode

lib/subutil/src/test/java/com/blankj/subutil/util/CoordinateUtilsTest.java

            
package com.blankj.subutil.util;

import org.junit.Assert;
import org.junit.Test;

import static java.lang.Math.PI;

/**
 * <pre>
 *     author: Blankj
 *     blog  : http://blankj.com
 *     time  : 2018/03/22
 *     desc  : CoordinateUtils 单元测试
 * </pre>
 */
public class CoordinateUtilsTest {

    // 以下为各个坐标系的 天安门坐标
    private static final double[] locationWGS84 = new double[]{116.3912022800, 39.9075017400};
    private static final double[] locationGCJ02 = new double[]{116.3973900000, 39.9088600000};
    private static final double[] locationBD09  = new double[]{116.4038206839, 39.9152478931};

    // 以下为美国纽约坐标
    private static final double[] newyorkWGS84 = new double[]{-74.0059413000, 40.7127837000};

    @Test
    public void gcj2BD09() throws Exception {
        double[] BD09 = CoordinateUtils.gcj02ToBd09(locationGCJ02[0], locationGCJ02[1]);
        double distance = distance(locationBD09[0], locationBD09[1], BD09[0], BD09[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    @Test
    public void bd092GCJ() {
        double[] GCJ02 = CoordinateUtils.bd09ToGcj02(locationBD09[0], locationBD09[1]);
        double distance = distance(locationGCJ02[0], locationGCJ02[1], GCJ02[0], GCJ02[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    @Test
    public void bd092WGS() {
        double[] WGS84 = CoordinateUtils.bd09ToWGS84(locationBD09[0], locationBD09[1]);
        double distance = distance(locationWGS84[0], locationWGS84[1], WGS84[0], WGS84[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    @Test
    public void wgs2BD09() {
        double[] BD09 = CoordinateUtils.wgs84ToBd09(locationWGS84[0], locationWGS84[1]);
        double distance = distance(locationBD09[0], locationBD09[1], BD09[0], BD09[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    @Test
    public void wgs2GCJ() {
        double[] GCJ02 = CoordinateUtils.wgs84ToGcj02(locationWGS84[0], locationWGS84[1]);
        double distance = distance(locationGCJ02[0], locationGCJ02[1], GCJ02[0], GCJ02[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    @Test
    public void gcj2WGS() {
        double[] WGS84 = CoordinateUtils.gcj02ToWGS84(locationGCJ02[0], locationGCJ02[1]);
        double distance = distance(locationWGS84[0], locationWGS84[1], WGS84[0], WGS84[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    @Test
    public void gcj2WGSExactly() {
        double[] WGS84 = CoordinateUtils.gcj02ToWGS84(locationGCJ02[0], locationGCJ02[1]);
        double distance = distance(locationWGS84[0], locationWGS84[1], WGS84[0], WGS84[1]);
        System.out.println("distance: " + distance);
        Assert.assertTrue(distance < 10);
    }

    public static double distance(double lngA, double latA, double lngB, double latB) {
        int earthR = 6371000;
        double x = Math.cos(latA * PI / 180) * Math.cos(latB * PI / 180) * Math.cos((lngA - lngB) * PI / 180);
        double y = Math.sin(latA * PI / 180) * Math.sin(latB * PI / 180);
        double s = x + y;
        if (s > 1)
            s = 1;
        if (s < -1)
            s = -1;
        double alpha = Math.acos(s);
        return alpha * earthR;
    }
}