Don't include an equal sign in the string representation of a Condition

pql/ast.go

@@ -161,7 +161,14 @@ func (c *Call) String() string {
 		if i > 0 {
 			buf.WriteString(", ")
 		}
-		fmt.Fprintf(&buf, "%v=%s", key, FormatValue(c.Args[key]))
+		// If the Arg value is a Condition, then don't include
+		// the equal sign in the string representation.
+		switch v := c.Args[key].(type) {
+		case *Condition:
+			fmt.Fprintf(&buf, "%v %s", key, v.String())
+		default:
+			fmt.Fprintf(&buf, "%v=%s", key, FormatValue(v))
+		}
 	}
 
 	// Write closing.

pql/ast_test.go

@@ -28,6 +28,18 @@ func TestCall_String(t *testing.T) {
 			t.Fatalf("unexpected string: %s", s)
 		}
 	})
+	t.Run("With Args", func(t *testing.T) {
+		c := &pql.Call{
+			Name: "Range",
+			Args: map[string]interface{}{
+				"frame":  "f",
+				"field0": &pql.Condition{Op: pql.GTE, Value: 10},
+			},
+		}
+		if s := c.String(); s != `Range(field0 >= 10, frame="f")` {
+			t.Fatalf("unexpected string: %s", s)
+		}
+	})
 }
 
 // Ensure call can be converted into a string.