Fix duration parsing error handling

src/main/java/org/opentripplanner/routing/api/request/framework/LinearFunctionSerialization.java

@@ -1,6 +1,7 @@
 package org.opentripplanner.routing.api.request.framework;
 
 import java.time.Duration;
+import java.time.format.DateTimeParseException;
 import java.util.Locale;
 import java.util.Optional;
 import java.util.function.BiFunction;
@@ -39,6 +40,8 @@ public class LinearFunctionSerialization {
     String.join(SEP, DUR, PLUS, NUM, VARIABLE)
   );
 
+  private static final Pattern DECIMAL_NUMBER_PATTERN = Pattern.compile("\\d+(\\.\\d+)?");
+
   private LinearFunctionSerialization() {}
 
   /**
@@ -61,11 +64,7 @@ public static <T> Optional<T> parse(String text, BiFunction<Duration, Double, T>
       var coefficient = Double.parseDouble(coefficientText);
       coefficient = Units.normalizedFactor(coefficient, 0.0, 100.0);
 
-      // Unfortunately, to be backwards compatible we need to support decimal numbers.
-      // If a decimal number, then the value is converted to seconds
-      var constant = constantText.matches("\\d+(\\.\\d+)?")
-        ? Duration.ofSeconds(IntUtils.round(Double.parseDouble(constantText)))
-        : DurationUtils.duration(constantText);
+      var constant = parseDecimalSecondsOrDuration(constantText);
 
       return Optional.of(factory.apply(constant, coefficient));
     }
@@ -85,4 +84,24 @@ public static String serialize(Duration constant, double coefficient) {
       Units.factorToString(coefficient)
     );
   }
+
+  /**
+   * Parse a String as a Duration.
+   * Unfortunately, to be backwards compatible we need to support decimal numbers.
+   * If the text represents a decimal number, then the value is converted to seconds.
+   * <br/>
+   * The parsing function {@link DurationUtils#parseSecondsOrDuration(String)} cannot be used
+   * here since it supports only integer seconds, not decimal seconds.
+   *
+   */
+  private static Duration parseDecimalSecondsOrDuration(String text) {
+    try {
+      if (DECIMAL_NUMBER_PATTERN.matcher(text).matches()) {
+        return Duration.ofSeconds(IntUtils.round(Double.parseDouble(text)));
+      }
+      return DurationUtils.duration(text);
+    } catch (DateTimeParseException e) {
+      throw new IllegalArgumentException("Unable to parse duration: '" + text + "'");
+    }
+  }
 }

src/test/java/org/opentripplanner/routing/api/request/framework/LinearFunctionSerializationTest.java

@@ -36,6 +36,8 @@ static Stream<Arguments> parseTestCases() {
            3h + 5.111 t   ||       3h  |   5.1
             7m + 10.1 x   ||       7m  |  10.0
           PT7s + 10.1 x   ||       7s  |  10.0
+          0.1 + 10.1 x   ||       0s  |  10.0
+          0.5 + 10.1 x   ||       1s  |  10.0
         """
     );
   }
@@ -53,7 +55,7 @@ void parseTest(String input, String expectedConstant, double expectedCoefficient
   }
 
   @Test
-  void parseEmtpy() {
+  void parseEmpty() {
     assertEquals(Optional.empty(), LinearFunctionSerialization.parse(null, fail()));
     assertEquals(Optional.empty(), LinearFunctionSerialization.parse("", fail()));
     assertEquals(Optional.empty(), LinearFunctionSerialization.parse(" \r\n", fail()));
@@ -77,6 +79,15 @@ void parseIllegalArgument() {
     assertEquals("Unable to parse function: 'foo'", ex.getMessage());
   }
 
+  @Test
+  void parseIllegalDuration() {
+    var ex = assertThrows(
+      IllegalArgumentException.class,
+      () -> LinearFunctionSerialization.parse("600ss + 1.3 t", fail())
+    );
+    assertEquals("Unable to parse duration: '600ss'", ex.getMessage());
+  }
+
   private static BiFunction<Duration, Double, ?> fail() {
     return (a, b) -> Assertions.fail("Factory method called, not expected!");
   }