Improve SAML tests resiliency to auto-formatting

test/framework/src/main/java/org/elasticsearch/common/util/NamedFormatter.java

@@ -0,0 +1,87 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.common.util;
+
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * A formatter that allows named placeholders e.g. "%(param)" to be replaced.
+ */
+public class NamedFormatter {
+    private static final Pattern PARAM_REGEX = Pattern
+        .compile(
+            // Match either any backlash-escaped characters, or a "%(param)" pattern.
+            // COMMENTS is specified to allow whitespace in this pattern, for clarity
+            "\\\\(.) | (% \\( ([^)]+) \\) )",
+            Pattern.COMMENTS
+        );
+
+    private NamedFormatter() {}
+
+    /**
+     * Replaces named parameters of the form <code>%(param)</code> in format strings. For example:
+     *
+     * <ul>
+     * <li><code>NamedFormatter.format("Hello, %(name)!", Map.of("name", "world"))</code> → <code>"Hello, world!"</code></li>
+     * <li><code>NamedFormatter.format("Hello, \%(name)!", Map.of("name", "world"))</code> → <code>"Hello, %(world)!"</code></li>
+     * <li><code>NamedFormatter.format("Hello, %(oops)!", Map.of("name", "world"))</code> → {@link IllegalArgumentException}</li>
+     * </ul>
+     *
+     * @param fmt The format string. Any <code>%(param)</code> is replaced by its corresponding value in the <code>values</code> map.
+     *             Parameter patterns can be escaped by prefixing with a backslash.
+     * @param values a map of parameter names to values.
+     * @return The formatted string.
+     * @throws IllegalArgumentException if a parameter is found in the format string with no corresponding value
+     */
+    public static String format(String fmt, Map<String, Object> values) {
+        final Matcher matcher = PARAM_REGEX.matcher(fmt);
+
+        boolean result = matcher.find();
+
+        if (result) {
+            final StringBuffer sb = new StringBuffer();
+            do {
+                String replacement;
+
+                // Escaped characters are unchanged
+                if (matcher.group(1) != null) {
+                    replacement = matcher.group(1);
+                } else {
+                    final String paramName = matcher.group(3);
+                    if (values.containsKey(paramName) == true) {
+                        replacement = values.get(paramName).toString();
+                    } else {
+                        throw new IllegalArgumentException("No parameter value for %(" + paramName + ")");
+                    }
+                }
+
+                matcher.appendReplacement(sb, replacement);
+                result = matcher.find();
+            } while (result);
+
+            matcher.appendTail(sb);
+            return sb.toString();
+        }
+
+        return fmt;
+    }
+}

test/framework/src/test/java/org/elasticsearch/common/util/NamedFormatterTests.java

@@ -0,0 +1,64 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.common.util;
+
+import org.elasticsearch.test.ESTestCase;
+import org.junit.Rule;
+import org.junit.rules.ExpectedException;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static java.util.Collections.singletonMap;
+import static org.hamcrest.Matchers.equalTo;
+
+public class NamedFormatterTests extends ESTestCase {
+    @Rule
+    public ExpectedException thrown = ExpectedException.none();
+
+    public void testPatternAreFormatted() {
+        assertThat(NamedFormatter.format("Hello, %(name)!", singletonMap("name", "world")), equalTo("Hello, world!"));
+    }
+
+    public void testDuplicatePatternsAreFormatted() {
+        assertThat(NamedFormatter.format("Hello, %(name) and %(name)!", singletonMap("name", "world")), equalTo("Hello, world and world!"));
+    }
+
+    public void testMultiplePatternsAreFormatted() {
+        final Map<String, Object> values = new HashMap<>();
+        values.put("name", "world");
+        values.put("second_name", "fred");
+
+        assertThat(
+            NamedFormatter.format("Hello, %(name) and %(second_name)!", values),
+            equalTo("Hello, world and fred!")
+        );
+    }
+
+    public void testEscapedPatternsAreNotFormatted() {
+        assertThat(NamedFormatter.format("Hello, \\%(name)!", singletonMap("name", "world")), equalTo("Hello, %(name)!"));
+    }
+
+    public void testUnknownPatternsThrowException() {
+        thrown.expect(IllegalArgumentException.class);
+        thrown.expectMessage("No parameter value for %(name)");
+        NamedFormatter.format("Hello, %(name)!", singletonMap("foo", "world"));
+    }
+}