fix(cron): Correctly detect if an expression is fuzzy or not (#549)

The current logic is flawed in that it just looks for the character `H`
hence an expression like `0 0 0 ? * MON-THU` will be considered fuzzy and will
be described correctly by `validateCronExpression`

echo-scheduler/src/main/java/com/netflix/spinnaker/echo/cron/CronExpressionFuzzer.java

@@ -47,7 +47,7 @@ public static boolean isValid(String expression) {
   }
 
   public static boolean hasFuzzyExpression(String expression) {
-    return expression.contains(TOKEN);
+    return Tokens.tokenize(expression).hasFuzzyToken();
   }
 
   private static class Tokens {
@@ -81,6 +81,10 @@ static Tokens tokenize(String expression) {
       return new Tokens(t[0], t[1], t[2], t[3], t[4], t[5], (t.length == 7) ? t[6] : null);
     }
 
+    boolean hasFuzzyToken() {
+      return seconds.contains(TOKEN) || minutes.contains(TOKEN) || hours.contains(TOKEN);
+    }
+
     String toFuzzedExpression(String id) {
       if (seconds.contains(TOKEN)) {
         seconds = seconds.replace(TOKEN, hash(id, 59));

echo-scheduler/src/test/groovy/com/netflix/spinnaker/echo/cron/CronExpressionFuzzerSpec.groovy

@@ -33,6 +33,24 @@ class CronExpressionFuzzerSpec extends Specification {
     "abcd"    | "H * * * * *"   || "34 * * * * *"
     "abcde"   | "* * H * * *"   || "* * 3 * * *"
     "abcd"    | "H/5 * * * * *" || "34/5 * * * * *"
+    "abcd"    | "00 05 09 ? * MON-THU" || "00 05 09 ? * MON-THU"
+  }
+
+  @Unroll
+  def "should correctly detect fuzz tokens"() {
+    when:
+    def result = CronExpressionFuzzer.hasFuzzyExpression(expression)
+
+    then:
+    result == expected
+
+    where:
+    expression      || expected
+    "H * * * * *"   || true
+    "* * H * * *"   || true
+    "H/5 * * * * *" || true
+    "H/5 * * * * THU" || true
+    "00 05 09 ? * MON-THU" || false
   }
 }
 

echo-web/src/test/java/com/netflix/spinnaker/echo/scheduler/ValidationControllerSpec.groovy

@@ -21,13 +21,13 @@ class ValidationControllerSpec extends Specification {
 
   void 'should include description when expression is valid'() {
     when:
-    def result = validate("0 0 10 ? * 1")
+    def result = validate("0 0 10 ? * THU")
 
     def responseBody = objectMapper.readValue(result.response.contentAsByteArray, Map)
 
     then:
     responseBody.response == "Cron expression is valid"
-    responseBody.description == "At 10:00 AM, only on Sunday"
+    responseBody.description == "At 10:00 AM, only on Thursday"
   }
 
   void 'should include failure message when expression is invalid'() {