Read ConfigurationParameters from properties file in classpath

WIP

Issue: #1003

junit-platform-engine/src/main/java/org/junit/platform/engine/ConfigurationParameters.java

@@ -31,6 +31,8 @@
 @API(Experimental)
 public interface ConfigurationParameters {
 
+	public static final String CONFIG_FILE_NAME = "junit-platform.properties";
+
 	/**
 	 * Get the configuration property stored under the specified {@code key}.
 	 *

junit-platform-launcher/src/main/java/org/junit/platform/launcher/core/LauncherConfigurationParameters.java

@@ -10,9 +10,14 @@
 
 package org.junit.platform.launcher.core;
 
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
+import java.util.Properties;
 
+import org.junit.platform.commons.util.ClassLoaderUtils;
 import org.junit.platform.commons.util.Preconditions;
 import org.junit.platform.commons.util.ToStringBuilder;
 import org.junit.platform.engine.ConfigurationParameters;
@@ -22,11 +27,41 @@
  */
 class LauncherConfigurationParameters implements ConfigurationParameters {
 
-	private final Map<String, String> configurationParameters;
+	// private static final Logger LOG = Logger.getLogger(LauncherConfigurationParameters.class.getName());
 
-	LauncherConfigurationParameters(Map<String, String> configurationParameters) {
-		Preconditions.notNull(configurationParameters, "configuration parameters must not be null");
-		this.configurationParameters = configurationParameters;
+	private final Map<String, String> configParams;
+
+	LauncherConfigurationParameters(Map<String, String> configParams) {
+		this(ConfigurationParameters.CONFIG_FILE_NAME, configParams);
+	}
+
+	LauncherConfigurationParameters(String configFileName, Map<String, String> configParams) {
+		Preconditions.notBlank(configFileName, "configFileName must not be null or blank");
+		Preconditions.notNull(configParams, "configuration parameters must not be null");
+		this.configParams = buildMap(configFileName, configParams);
+	}
+
+	private static Map<String, String> buildMap(String configFileName, Map<String, String> configParams) {
+		Map<String, String> map = new HashMap<>();
+
+		Properties props = new Properties();
+		try {
+			InputStream inputStream = ClassLoaderUtils.getDefaultClassLoader().getResourceAsStream(configFileName);
+			if (inputStream != null) {
+				// TODO Log info message stating that the config file was found.
+				props.load(inputStream);
+				props.forEach((key, value) -> map.put(String.valueOf(key), String.valueOf(value)));
+			}
+		}
+		catch (IOException ex) {
+			// TODO Log warning.
+		}
+
+		// Override properties loaded from config file with values supplied via
+		// the Launcher API.
+		configParams.forEach(map::put);
+
+		return map;
 	}
 
 	@Override
@@ -45,12 +80,12 @@ public Optional<Boolean> getBoolean(String key) {
 
 	@Override
 	public int size() {
-		return this.configurationParameters.size();
+		return this.configParams.size();
 	}
 
 	private String getProperty(String key) {
 		Preconditions.notBlank(key, "key must not be null or blank");
-		String value = this.configurationParameters.get(key);
+		String value = this.configParams.get(key);
 		if (value == null) {
 			try {
 				value = System.getProperty(key);
@@ -65,7 +100,7 @@ private String getProperty(String key) {
 	@Override
 	public String toString() {
 		ToStringBuilder builder = new ToStringBuilder(this);
-		this.configurationParameters.forEach(builder::append);
+		this.configParams.forEach(builder::append);
 		return builder.toString();
 	}
 

platform-tests/src/test/java/org/junit/platform/launcher/core/LauncherConfigurationParametersTests.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2015-2017 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v1.0 which
+ * accompanies this distribution and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package org.junit.platform.launcher.core;
+
+/**
+ * Unit tests for {@link LauncherConfigurationParameters}.
+ *
+ * @since 1.0
+ */
+class LauncherConfigurationParametersTests {
+
+}