Ticket #15508: v4-0002-add-TileSourceRule-a-junit-rule-for-creating-mock-ti.patch

new file test/unit/org/openstreetmap/josm/testutils/TileSourceRule.java

@@ +1 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.testutils;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Objects;
+import java.util.HashMap;
+import java.util.List;
+
+import java.awt.Color;
+import java.awt.Graphics2D;
+import java.awt.image.BufferedImage;
+
+import javax.imageio.ImageIO;
+
+import org.openstreetmap.josm.data.imagery.ImageryInfo;
+import org.openstreetmap.josm.data.imagery.ImageryLayerInfo;
+import org.openstreetmap.josm.gui.bbox.SlippyMapBBoxChooser;
+import org.openstreetmap.josm.tools.Logging;
+
+import static org.openstreetmap.josm.TestUtils.getPrivateStaticField;
+
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+import com.github.tomakehurst.wiremock.client.MappingBuilder;
+import com.github.tomakehurst.wiremock.client.ResponseDefinitionBuilder;
+import com.github.tomakehurst.wiremock.client.WireMock;
+import com.github.tomakehurst.wiremock.junit.WireMockRule;
+
+import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.options;
+
+
+/**
+ * A JUnit rule, based on {@link WireMockRule} to provide a test with a simple mock tile server serving multiple tile
+ * sources.
+ */
+public class TileSourceRule extends WireMockRule {
+    private static class ByteArrayWrapper {
+        // i don't believe you're making me do this, java
+        public final byte[] byteArray;
+
+        ByteArrayWrapper(byte[] ba) {
+            this.byteArray = ba;
+        }
+    }
+
+    // allocation is expensive and many tests may be wanting to set up the same tile sources one after the other, hence
+    // this cache
+    public static HashMap<ConstSource, ByteArrayWrapper> constPayloadCache = new HashMap<>();
+
+    /**
+     * Class defining a tile source for TileSourceRule to mock. Due to the way WireMock is designed, it is far more
+     * straightforward to serve a single image in all tile positions 
+     */
+    public abstract static class ConstSource {
+        /**
+         * method for actually generating the payload body bytes, uncached
+         */
+        public abstract byte[] generatePayloadBytes();
+
+        /**
+         * @return a {@link MappingBuilder} representing the request matching properties of this tile source, suitable
+         * for passing to {@link WireMockRule#stubFor}.
+         */
+        public abstract MappingBuilder getMappingBuilder();
+
+        /**
+         * @return text label/name for this source if displayed in JOSM menus
+         */
+        public abstract String getLabel();
+
+        /**
+         * @param port the port this WireMock server is running on
+         * @return {@link ImageryInfo} describing this tile source, as might be submitted to {@link ImageryLayerInfo#add}
+         */
+        public abstract ImageryInfo getImageryInfo(int port);
+
+        /**
+         * @return byte array of the payload body for this source, possibly retrieved from a global cache
+         */
+        public byte[] getPayloadBytes() {
+            ByteArrayWrapper payloadWrapper = constPayloadCache.get(this);
+            if (payloadWrapper == null) {
+                payloadWrapper = new ByteArrayWrapper(this.generatePayloadBytes());
+                constPayloadCache.put(this, payloadWrapper);
+            }
+            return payloadWrapper.byteArray;
+        }
+
+        /**
+         * @return a {@link ResponseDefinitionBuilder} embodying the payload of this tile source suitable for
+         * application to a {@link MappingBuilder}.
+         */
+        public ResponseDefinitionBuilder getResponseDefinitionBuilder() {
+            return WireMock.aResponse().withStatus(200).withHeader("Content-Type", "image/png").withBody(
+                this.getPayloadBytes()
+            );
+        }
+    }
+
+    /**
+     * A plain color tile source
+     */
+    public static class ColorSource extends ConstSource {
+        protected final Color color;
+        protected final String label;
+        protected final int tileSize;
+
+        /**
+         * @param color Color for these tiles
+         * @param label text label/name for this source if displayed in JOSM menus
+         * @param tileSize Pixel dimension of tiles (usually 256)
+         */
+        public ColorSource(Color color, String label, int tileSize) {
+            this.color = color;
+            this.label = label;
+            this.tileSize = tileSize;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(this.color, this.label, this.tileSize, this.getClass());
+        }
+
+        @Override
+        public byte[] generatePayloadBytes() {
+            BufferedImage image = new BufferedImage(this.tileSize, this.tileSize, BufferedImage.TYPE_INT_RGB);
+            Graphics2D g = image.createGraphics();
+            g.setBackground(this.color);
+            g.clearRect(0, 0, image.getWidth(), image.getHeight());
+
+            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+            try {
+                ImageIO.write(image, "png", outputStream);
+            // CHECKSTYLE.OFF: EmptyBlock
+            } catch (IOException e) {
+                // I don't see how this would be possible writing to a ByteArrayOutputStream
+            }
+            // CHECKSTYLE.ON: EmptyBlock
+            return outputStream.toByteArray();
+        }
+
+        @Override
+        public MappingBuilder getMappingBuilder() {
+            return WireMock.get(WireMock.urlMatching(String.format("/%h/(\\d+)/(\\d+)/(\\d+)\\.png", this.hashCode())));
+        }
+
+        @Override
+        public ImageryInfo getImageryInfo(int port) {
+            return new ImageryInfo(
+                this.label,
+                String.format("tms[20]:http://localhost:%d/%h/{z}/{x}/{y}.png", port, this.hashCode()),
+                "tms",
+                (String) null,
+                (String) null
+            );
+        }
+
+        @Override
+        public String getLabel() {
+            return this.label;
+        }
+    }
+
+    public final List<ConstSource> sourcesList;
+    public final boolean clearLayerList;
+    public final boolean clearSlippyMapSources;
+    public final boolean registerInLayerList;
+
+    /**
+     * Construct a TileSourceRule for use with a JUnit test.
+     *
+     * This variant will not make any attempt to register the sources' existence with any JOSM subsystems, so is safe
+     * for direct application to a JUnit test.
+     *
+     * @param sources tile sources to serve from this mock server
+     */
+    public TileSourceRule(ConstSource... sources) {
+        this(false, false, false, sources);
+    }
+
+    /**
+     * Construct a TileSourceRule for use with a JUnit test.
+     *
+     * The three boolean parameters control whether to perform various steps registering the tile sources with parts
+     * of JOSM's internals as part of the setup process. It is advised to only enable any of these if it can be ensured
+     * that this rule will have its setup routine executed *after* the relevant parts of JOSM have been set up, e.g.
+     * when handled by {@link org.openstreetmap.josm.testutils.JOSMTestRules#fakeImagery}.
+     *
+     * @param clearLayerList whether to clear ImageryLayerInfo's layer list of any pre-existing entries
+     * @param clearSlippyMapSources whether to clear SlippyMapBBoxChooser's stubborn fallback Mapnik TileSource
+     * @param registerInLayerList whether to add sources to ImageryLayerInfo's layer list
+     * @param sources tile sources to serve from this mock server
+     */
+    public TileSourceRule(
+        boolean clearLayerList,
+        boolean clearSlippyMapSources,
+        boolean registerInLayerList,
+        ConstSource... sources
+    ) {
+        super(options().dynamicPort());
+        this.clearLayerList = clearLayerList;
+        this.clearSlippyMapSources = clearSlippyMapSources;
+        this.registerInLayerList = registerInLayerList;
+
+        // set up a stub target for the early request hack
+        this.stubFor(WireMock.get(
+            WireMock.urlMatching("/_poke")
+        ).willReturn(
+            WireMock.aResponse().withStatus(200).withBody("ow.")
+        ));
+
+        this.sourcesList = Collections.unmodifiableList(Arrays.asList(sources));
+        for (ConstSource source : this.sourcesList) {
+            this.stubFor(source.getMappingBuilder().willReturn(source.getResponseDefinitionBuilder()));
+        }
+    }
+
+    /**
+     * A junit-rule {@code apply} method exposed separately to allow a chaining rule to put this much earlier in
+     * the test's initialization routine. The idea being to allow WireMock's web server to be starting up while other
+     * necessary initialization is taking place.
+     * See {@link org.junit.rules.TestRule#apply} for arguments.
+     */
+    public Statement applyRunServer(Statement base, Description description) {
+        return super.apply(new Statement() {
+            @Override
+            public void evaluate() throws Throwable {
+                try {
+                    // a hack to circumvent a WireMock bug concerning delayed server startup. sending an early request
+                    // to the mock server seems to prompt it to start earlier (though this request itself is not
+                    // expected to succeed). see https://github.com/tomakehurst/wiremock/issues/97
+                    (new java.net.URL(String.format("http://localhost:%d/_poke", TileSourceRule.this.port()))).getContent();
+                // CHECKSTYLE.OFF: EmptyBlock
+                } catch (Throwable t) {
+                    // don't care
+                }
+                // CHECKSTYLE.ON: EmptyBlock
+                base.evaluate();
+            }
+        }, description);
+    }
+
+    /**
+     * A junit-rule {@code apply} method exposed separately, containing initialization steps which can only be performed
+     * once more of josm's environment has been set up.
+     * See {@link org.junit.rules.TestRule#apply} for arguments.
+     */
+    public Statement applyRegisterLayers(Statement base, Description description) {
+        if (this.registerInLayerList || this.clearLayerList) {
+            return new Statement() {
+                @Override
+                @SuppressWarnings("unchecked")
+                public void evaluate() throws Throwable {
+                    List<SlippyMapBBoxChooser.TileSourceProvider> slippyMapProviders = null;
+                    SlippyMapBBoxChooser.TileSourceProvider slippyMapDefaultProvider = null;
+                    List<ImageryInfo> originalImageryInfoList = null;
+                    if (TileSourceRule.this.clearSlippyMapSources) {
+                        try {
+                            slippyMapProviders = (List<SlippyMapBBoxChooser.TileSourceProvider>) getPrivateStaticField(
+                                SlippyMapBBoxChooser.class,
+                                "providers"
+                            );
+                            // pop this off the beginning of the list, keep for later
+                            slippyMapDefaultProvider = slippyMapProviders.remove(0);
+                        } catch (ReflectiveOperationException e) {
+                            Logging.warn("Failed to remove default SlippyMapBBoxChooser TileSourceProvider");
+                        }
+                    }
+
+                    if (TileSourceRule.this.clearLayerList) {
+                        originalImageryInfoList = ImageryLayerInfo.instance.getLayers();
+                        ImageryLayerInfo.instance.clear();
+                    }
+                    if (TileSourceRule.this.registerInLayerList) {
+                        for (ConstSource source : TileSourceRule.this.sourcesList) {
+                            ImageryLayerInfo.addLayer(source.getImageryInfo(TileSourceRule.this.port()));
+                        }
+                    }
+
+                    try {
+                        base.evaluate();
+                    } finally {
+                        // clean up to original state
+                        if (slippyMapDefaultProvider != null) {
+                            slippyMapProviders.add(0, slippyMapDefaultProvider);
+                        }
+                        if (originalImageryInfoList != null) {
+                            ImageryLayerInfo.instance.clear();
+                            ImageryLayerInfo.addLayers(originalImageryInfoList);
+                        }
+                    }
+                }
+            };
+        } else {
+            return base;
+        }
+    }
+
+    /**
+     * A standard implementation of apply which simply calls both sub- {@code apply} methods, {@link #applyRunServer}
+     * and {@link applyRegisterLayers}. Called when used as a standard junit rule.
+     */
+    @Override
+    public Statement apply(Statement base, Description description) {
+        return this.applyRunServer(this.applyRegisterLayers(base, description), description);
+    }
+}