additional tests for contains and trigrams (#1078)

Put in some additional test cases for extracting contained
strings and trigrams from patterns. Fixes some cases with
trigram extraction for repeats that can be absent from the
string and still match.

spectator-api/src/main/java/com/netflix/spectator/impl/matcher/CharSeqMatcher.java

@@ -48,6 +48,11 @@ String pattern() {
     return pattern;
   }
 
+  @Override
+  public String containedString() {
+    return pattern;
+  }
+
   @Override
   public SortedSet<String> trigrams() {
     return PatternUtils.computeTrigrams(pattern);

spectator-api/src/main/java/com/netflix/spectator/impl/matcher/RepeatMatcher.java

@@ -16,6 +16,7 @@
 package com.netflix.spectator.impl.matcher;
 
 import java.io.Serializable;
+import java.util.Collections;
 import java.util.Objects;
 import java.util.SortedSet;
 import java.util.function.Function;
@@ -48,9 +49,14 @@ int max() {
     return max;
   }
 
+  @Override
+  public String containedString() {
+    return min == 0 ? null : repeated.containedString();
+  }
+
   @Override
   public SortedSet<String> trigrams() {
-    return repeated.trigrams();
+    return min == 0 ? Collections.emptySortedSet() : repeated.trigrams();
   }
 
   @Override

spectator-api/src/main/java/com/netflix/spectator/impl/matcher/SeqMatcher.java

@@ -80,7 +80,12 @@ public String prefix() {
 
   @Override
   public String containedString() {
-    return matchers[0].containedString();
+    String str = null;
+    for (Matcher m : matchers) {
+      str = m.containedString();
+      if (str != null) break;
+    }
+    return str;
   }
 
   @Override

spectator-api/src/main/java/com/netflix/spectator/impl/matcher/ZeroOrMoreMatcher.java

@@ -20,7 +20,6 @@
 import java.io.Serializable;
 import java.util.Objects;
 import java.util.SortedSet;
-import java.util.TreeSet;
 import java.util.function.Function;
 
 /**
@@ -49,12 +48,14 @@ Matcher next() {
     return next;
   }
 
+  @Override
+  public String containedString() {
+    return next.containedString();
+  }
+
   @Override
   public SortedSet<String> trigrams() {
-    SortedSet<String> ts = new TreeSet<>();
-    ts.addAll(repeated.trigrams());
-    ts.addAll(next.trigrams());
-    return ts;
+    return next.trigrams();
   }
 
   @Override

spectator-api/src/main/java/com/netflix/spectator/impl/matcher/ZeroOrOneMatcher.java

@@ -20,7 +20,6 @@
 import java.io.Serializable;
 import java.util.Objects;
 import java.util.SortedSet;
-import java.util.TreeSet;
 import java.util.function.Function;
 
 /**
@@ -49,12 +48,14 @@ Matcher next() {
     return next;
   }
 
+  @Override
+  public String containedString() {
+    return next.containedString();
+  }
+
   @Override
   public SortedSet<String> trigrams() {
-    SortedSet<String> ts = new TreeSet<>();
-    ts.addAll(repeated.trigrams());
-    ts.addAll(next.trigrams());
-    return ts;
+    return next.trigrams();
   }
 
   @Override

spectator-api/src/test/java/com/netflix/spectator/impl/matcher/AbstractPatternMatcherTest.java

@@ -421,6 +421,14 @@ public void zeroOrMoreWithOr() {
     testRE("(a|b|c)*d", "ababcd");
   }
 
+  @Test
+  public void repeatZero() {
+    testRE("(abc){0,3}def", "def");
+    testRE("(abc){0,3}def", "abcdef");
+    testRE("(abc){1,3}def", "def");
+    testRE("(abc){1,3}def", "abcdef");
+  }
+
   @Test
   public void repeatWithOr() {
     testRE("(a|b|c){1,3}d", "aaad");

spectator-api/src/test/java/com/netflix/spectator/impl/matcher/ContainsPatternMatcherTest.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2014-2023 Netflix, Inc.
+ *
+ * Licensed 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 com.netflix.spectator.impl.matcher;
+
+import com.netflix.spectator.impl.PatternMatcher;
+import org.junit.jupiter.api.Assertions;
+
+public class ContainsPatternMatcherTest extends AbstractPatternMatcherTest {
+
+  @Override
+  protected void testRE(String regex, String value) {
+    PatternMatcher matcher = PatternMatcher.compile(regex);
+    String str = matcher.containedString();
+
+    // Contains should be more lenient than the actual pattern, so anything that is matched
+    // by the pattern must be a possible match with the trigrams.
+    if (str != null && matcher.matches(value)) {
+      Assertions.assertTrue(value.contains(str));
+    }
+  }
+}

spectator-api/src/test/java/com/netflix/spectator/impl/matcher/ContainsTest.java

@@ -68,10 +68,46 @@ public void notContains() {
   public void containedString() {
     Assertions.assertEquals("abc", re("abc").containedString());
     Assertions.assertEquals("abc", re(".*abc").containedString());
+    Assertions.assertEquals("abc", re(".*abc$").containedString());
     Assertions.assertEquals("ab", re(".*ab[cd]").containedString());
     Assertions.assertEquals("abc", re("abc.def").containedString());
     Assertions.assertEquals("abc.def", re("abc\\.def").containedString());
     Assertions.assertEquals("abc", re("^abc.def").containedString());
     Assertions.assertEquals("abc.def", re("^abc\\.def").containedString());
   }
+
+  @Test
+  public void containsZeroOrMore() {
+    Assertions.assertEquals("def", re("(abc)*def").containedString());
+  }
+
+  @Test
+  public void containsZeroOrOne() {
+    Assertions.assertEquals("def", re("(abc)?def").containedString());
+  }
+
+  @Test
+  public void containsOneOrMore() {
+    Assertions.assertEquals("abc", re("(abc)+def").containedString());
+  }
+
+  @Test
+  public void containsRepeat() {
+    Assertions.assertEquals("def", re("(abc){0,5}def").containedString());
+  }
+
+  @Test
+  public void containsRepeatAtLeastOne() {
+    Assertions.assertEquals("abc", re("(abc){1,5}def").containedString());
+  }
+
+  @Test
+  public void containsPartOfSequence() {
+    Assertions.assertEquals("abcd", re(".*[0-9]abcd[efg]hij").containedString());
+  }
+
+  @Test
+  public void containsMultiple() {
+    Assertions.assertEquals("abc", re("^abc.*def.*ghi").containedString());
+  }
 }

spectator-api/src/test/java/com/netflix/spectator/impl/matcher/TrigramsPatternMatcherTest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2014-2023 Netflix, Inc.
+ *
+ * Licensed 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 com.netflix.spectator.impl.matcher;
+
+import com.netflix.spectator.impl.PatternMatcher;
+import org.junit.jupiter.api.Assertions;
+
+import java.util.SortedSet;
+
+public class TrigramsPatternMatcherTest extends AbstractPatternMatcherTest {
+
+  @Override
+  protected void testRE(String regex, String value) {
+    PatternMatcher matcher = PatternMatcher.compile(regex);
+    SortedSet<String> trigrams = matcher.trigrams();
+
+    // Trigrams should be more lenient than the actual pattern, so anything that is matched
+    // by the pattern must be a possible match with the trigrams.
+    if (matcher.matches(value)) {
+      Assertions.assertTrue(couldMatch(trigrams, value));
+    }
+  }
+
+  private boolean couldMatch(SortedSet<String> trigrams, String value) {
+    return trigrams.stream().allMatch(value::contains);
+  }
+}

spectator-api/src/test/java/com/netflix/spectator/impl/matcher/TrigramsTest.java

@@ -48,13 +48,13 @@ public void endsWith() {
   @Test
   public void zeroOrMore() {
     PatternMatcher m = PatternMatcher.compile("(abc)*def");
-    Assertions.assertEquals(sortedSet("abc", "def"), m.trigrams());
+    Assertions.assertEquals(sortedSet("def"), m.trigrams());
   }
 
   @Test
   public void zeroOrOne() {
     PatternMatcher m = PatternMatcher.compile("(abc)?def");
-    Assertions.assertEquals(sortedSet("abc", "def"), m.trigrams());
+    Assertions.assertEquals(sortedSet("def"), m.trigrams());
   }
 
   @Test
@@ -66,6 +66,12 @@ public void oneOrMore() {
   @Test
   public void repeat() {
     PatternMatcher m = PatternMatcher.compile("(abc){0,5}def");
+    Assertions.assertEquals(sortedSet("def"), m.trigrams());
+  }
+
+  @Test
+  public void repeatAtLeastOne() {
+    PatternMatcher m = PatternMatcher.compile("(abc){1,5}def");
     Assertions.assertEquals(sortedSet("abc", "def"), m.trigrams());
   }