Allow duration / duration in TICKscript (influxdata#909)

* allow duration / duration in TICKscript

* CHANGELOG.md

CHANGELOG.md

@@ -10,6 +10,7 @@
 - [#869](https://github.com/influxdata/kapacitor/issues/869): Add ability to set alert message as a field
 - [#854](https://github.com/influxdata/kapacitor/issues/854): Add `.create` property to InfluxDBOut node, which when set will create the database
     and retention policy on task start.
+- [#909](https://github.com/influxdata/kapacitor/pull/909): Allow duration / duration in TICKscript.
 
 ### Bugfixes
 

tick/stateful/evaluation_funcs.go

@@ -1208,6 +1208,24 @@ var evaluationFuncs = map[operationKey]*evaluationFnInfo{
 		},
 		returnType: ast.TDuration,
 	},
+	operationKey{operator: ast.TokenDiv, leftType: ast.TDuration, rightType: ast.TDuration}: {
+		f: func(scope *Scope, executionState ExecutionState, leftNode, rightNode NodeEvaluator) (resultContainer, *ErrSide) {
+			var left time.Duration
+			var right time.Duration
+			var err error
+
+			if left, err = leftNode.EvalDuration(scope, executionState); err != nil {
+				return emptyResultContainer, &ErrSide{error: err, IsLeft: true}
+			}
+
+			if right, err = rightNode.EvalDuration(scope, executionState); err != nil {
+				return emptyResultContainer, &ErrSide{error: err, IsRight: true}
+			}
+
+			return resultContainer{Int64Value: int64(left / right), IsInt64Value: true}, nil
+		},
+		returnType: ast.TInt,
+	},
 
 	// -----------------------------------------
 	//	String concatenation func

tick/stateful/expr_test.go

@@ -175,10 +175,12 @@ func TestExpression_EvalDuration(t *testing.T) {
 		// Left is time.Duration(5), Right is time.Duration(5)
 		keyStruct{time.Duration(5), time.Duration(5), ast.TokenPlus}:  time.Duration(10),
 		keyStruct{time.Duration(5), time.Duration(5), ast.TokenMinus}: time.Duration(0),
+		keyStruct{time.Duration(5), time.Duration(5), ast.TokenDiv}:   int64(1),
 
 		// Left is time.Duration(5), Right is time.Duration(10)
 		keyStruct{time.Duration(5), time.Duration(10), ast.TokenPlus}:  time.Duration(15),
 		keyStruct{time.Duration(5), time.Duration(10), ast.TokenMinus}: time.Duration(-5),
+		keyStruct{time.Duration(5), time.Duration(10), ast.TokenDiv}:   int64(0),
 
 		// Left is time.Duration(5), Right is int64(2)
 		keyStruct{time.Duration(5), int64(2), ast.TokenMult}: time.Duration(10),
@@ -191,10 +193,12 @@ func TestExpression_EvalDuration(t *testing.T) {
 		// Left is time.Duration(10), Right is time.Duration(5)
 		keyStruct{time.Duration(10), time.Duration(5), ast.TokenPlus}:  time.Duration(15),
 		keyStruct{time.Duration(10), time.Duration(5), ast.TokenMinus}: time.Duration(5),
+		keyStruct{time.Duration(10), time.Duration(5), ast.TokenDiv}:   int64(2),
 
 		// Left is time.Duration(10), Right is time.Duration(10)
 		keyStruct{time.Duration(10), time.Duration(10), ast.TokenPlus}:  time.Duration(20),
 		keyStruct{time.Duration(10), time.Duration(10), ast.TokenMinus}: time.Duration(0),
+		keyStruct{time.Duration(10), time.Duration(10), ast.TokenDiv}:   int64(1),
 
 		// Left is time.Duration(10), Right is int64(2)
 		keyStruct{time.Duration(10), int64(2), ast.TokenMult}: time.Duration(20),
@@ -235,13 +239,9 @@ func TestExpression_EvalDuration(t *testing.T) {
 
 		// Muiltiply Divide durations
 		keyStruct{time.Duration(5), time.Duration(5), ast.TokenMult}:   errors.New("mismatched type to binary operator. got duration * duration. see bool(), int(), float(), string(), duration()"),
-		keyStruct{time.Duration(5), time.Duration(5), ast.TokenDiv}:    errors.New("mismatched type to binary operator. got duration / duration. see bool(), int(), float(), string(), duration()"),
 		keyStruct{time.Duration(5), time.Duration(10), ast.TokenMult}:  errors.New("mismatched type to binary operator. got duration * duration. see bool(), int(), float(), string(), duration()"),
-		keyStruct{time.Duration(5), time.Duration(10), ast.TokenDiv}:   errors.New("mismatched type to binary operator. got duration / duration. see bool(), int(), float(), string(), duration()"),
 		keyStruct{time.Duration(10), time.Duration(10), ast.TokenMult}: errors.New("mismatched type to binary operator. got duration * duration. see bool(), int(), float(), string(), duration()"),
-		keyStruct{time.Duration(10), time.Duration(10), ast.TokenDiv}:  errors.New("mismatched type to binary operator. got duration / duration. see bool(), int(), float(), string(), duration()"),
 		keyStruct{time.Duration(10), time.Duration(5), ast.TokenMult}:  errors.New("mismatched type to binary operator. got duration * duration. see bool(), int(), float(), string(), duration()"),
-		keyStruct{time.Duration(10), time.Duration(5), ast.TokenDiv}:   errors.New("mismatched type to binary operator. got duration / duration. see bool(), int(), float(), string(), duration()"),
 
 		// Add/Subtract duration with int/float
 		keyStruct{time.Duration(5), int64(2), ast.TokenPlus}:       errors.New("mismatched type to binary operator. got duration + int. see bool(), int(), float(), string(), duration()"),
@@ -1503,6 +1503,9 @@ func runCompiledEvalTests(
 				if !isExpectedResultOk && !isErrorOk {
 					t.Fatalf("Couldn't find an expected result/error for: lhs: %v, rhs: %v, op: %v", lhs, rhs, op)
 				}
+				if isExpectedResultOk && isErrorOk {
+					t.Fatalf("Found both an expected result and an expected error for: lhs: %v, rhs: %v, op: %v", lhs, rhs, op)
+				}
 
 				// Test simple const values compares
 				emptyScope := stateful.NewScope()