Testing & evaluation
Custom symbols in MT5: create a small reproducible price experiment
A controlled price sequence can answer a narrow question such as whether a trailing rule moves once or whether a pending order survives a gap. Custom symbols help isolate that behaviour from the thousands of unrelated events in a long market history.
Separate fixture and market data
MQL5 provides functions for creating custom symbols and managing their rates and ticks. A custom symbol is not automatically a tradable broker instrument. Its properties and data must be deliberately prepared for the experiment.
Design one path
An illustrative fixture might rise, pause, retrace and rise again. State the intended entry and exit observations before running it. Preserve the generated timestamps and prices, and avoid selecting only the path that makes the EA look best.
Freeze the specification
Record tick size, contract settings, volume rules, costs and the supplied data file alongside the EA build and inputs. If these change between runs, a different result may come from the environment rather than the code change.
Use it as a development tool
Ask AI to explain which branch the fixture exercises and which behaviours it leaves untested. Label any resulting chart as a synthetic scenario. Use ordinary broker-data testing separately for historical evaluation; the small experiment answers a different, more focused question.
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