Cron and Interval check scheduling are now mutually exclusive (#941)

* Cron and Interval check scheduling are now mutually exclusive

Signed-off-by: Greg Poirier <greg.istehbest@gmail.com>

CHANGELOG.md

@@ -16,6 +16,7 @@ Versioning](http://semver.org/spec/v2.0.0.html).
 
 ### Changed
 - Govaluate logic is now wrapped in the `util/eval` package.
+- Cron and Interval scheduling are now mutually exclusive.
 
 ### Fixed
 - Fixed a bug where retrieving check hooks were only from the check's

testing/e2e/check_scheduling_test.go

@@ -96,6 +96,7 @@ func TestCheckScheduling(t *testing.T) {
 	assert.NotEqual(t, count2, count3)
 
 	// Change the check schedule to cron
+	check.Interval = 0
 	check.Cron = "* * * * *"
 	err = sensuClient.UpdateCheck(check)
 	assert.NoError(t, err)

types/check.go

@@ -58,15 +58,23 @@ func (c *CheckConfig) Validate() error {
 	}
 
 	if c.Cron != "" {
+		if c.Interval != 0 {
+			return errors.New("must only specify either an interval or a cron schedule")
+		}
+
 		if _, err := cron.ParseStandard(c.Cron); err != nil {
 			return errors.New("check cron string is invalid")
 		}
 	}
 
-	if c.Interval == 0 {
+	if c.Interval == 0 && c.Cron == "" {
 		return errors.New("check interval must be greater than 0")
 	}
 
+	if c.Interval > 0 && c.Cron != "" {
+		return errors.New("must only specify either an interval or a cron schedule")
+	}
+
 	if c.Environment == "" {
 		return errors.New("environment cannot be empty")
 	}

types/check_test.go

@@ -49,10 +49,6 @@ func TestCheckConfig(t *testing.T) {
 	assert.Error(t, c.Validate())
 	c.Interval = 60
 
-	// Invalid cron
-	assert.Error(t, c.Validate())
-	c.Cron = "* * * * *"
-
 	// Invalid command
 	assert.Error(t, c.Validate())
 	c.Command = "echo 'foo'"
@@ -74,6 +70,23 @@ func TestCheckConfig(t *testing.T) {
 	assert.NoError(t, c.Validate())
 }
 
+func TestScheduleValidation(t *testing.T) {
+	c := FixtureCheck("check")
+	config := c.Config
+
+	// Fixture comes with valid interval-based schedule
+	assert.NoError(t, config.Validate())
+
+	config.Cron = "* * * * *"
+	assert.Error(t, config.Validate())
+
+	config.Interval = 0
+	assert.NoError(t, config.Validate())
+
+	config.Cron = "this is an invalid cron"
+	assert.Error(t, config.Validate())
+}
+
 func TestFixtureCheckIsValid(t *testing.T) {
 	c := FixtureCheck("check")
 	config := c.Config