---
source_files:
  - DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.TestModification/Model/Enums.cs
  - DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.TestModification/Model/TestModificationModel.cs
  - DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.TestModification/Model/TestModelManipulation.cs
generated_at: "2026-04-17T15:55:05.952766+00:00"
model: "zai-org/GLM-5-FP8"
schema_version: 1
sha256: "8c9823f92db20638"
---

# Test Modification Module Documentation

## 1. Purpose

This module provides functionality for modifying test data within the DTS Viewer application. It enables users to adjust channel parameters (sensitivity, EU multiplier/offset, T0 time shifts, line fit, software filters, data flags, and descriptions) and persist those changes to both binary channel files (`.chn`) and test configuration files (`.dts`). The module implements a backup-and-restore system to allow reverting modifications, and tracks modification state to indicate unsaved changes to the user interface.

---

## 2. Public Interface

### Enums.cs

#### `Keys` Enum
```csharp
public enum Keys
{
    ApplyShiftT0ModsTestOnly // System Setting for whether to restrict "Shift T0" test modifications to "Test" only.
}
```
A configuration key enum used to control T0 modification behavior restrictions.

---

### TestModificationModel.cs

#### `TestModificationModel` Class
Implements `ITestModificationModel` and provides `INotifyPropertyChanged` for data binding.

**Calibration Properties:**
- `string CalDate` — Read-only; returns `Cal.CalibrationDate.ToShortDateString()` or empty string if `Cal` is null.
- `string ModifyDate` — Read-only; returns formatted modify date/time or empty string if `Cal` is null.
- `double CalSensitivity` — Gets/sets sensitivity from `Cal.Records.Records[0].Sensitivity`; returns `double.NaN` if unavailable.
- `bool ProportionalToExcitation` — Read-only; returns `Cal.IsProportional`.
- `bool NonLinear` — Read-only; returns `Cal.NonLinear`.
- `bool ShowSensorCal` — Read-only; returns true if `Cal` and `Sensor` are non-null and `NonLinear` is false.
- `ISensorCalDbRecord Cal` — Gets/sets the latest calibration record; triggers `RebindCalProperties()` on set.
- `ISensorDbRecord Sensor` — Gets/sets the sensor record; triggers `RebindCalProperties()` on set.

**Channel Selection:**
- `ITestChannel SelectedChannel` — The currently selected channel for modification.

**Modification Value Properties:**
- `string Description` — Channel description text.
- `double EuMultiplier` — EU multiplier value.
- `double EuOffset` — EU offset value.
- `double T0` — T0 time shift value (milliseconds).
- `double T1` — Line fit start point (milliseconds).
- `double T2` — Line fit end point (milliseconds).
- `double Sensitivity` — Channel sensitivity value.
- `IFilterClass SelectedFilter` — Selected software filter; defaults to `FilterClass(FilterClassType.Unfiltered)`.
- `DataFlag SelectedDataFlag` — Selected data flag; defaults to `DataFlag.None`.
- `T0Mode T0Mode` — T0 application mode (`T0Mode.Test` or `T0Mode.DAS`); defaults to `T0Mode.Test`.

**Modification State Properties (Read-only):**
- `bool IsModifiedDescription` — True if `Description` differs from `SelectedChannel.ChannelDescriptionString`.
- `bool IsModifiedEuMultiplier` — True if `EuMultiplier` differs from `SelectedChannel.Multiplier`.
- `bool IsModifiedEuOffset` — True if `EuOffset` differs from `SelectedChannel.UserOffsetEu`.
- `bool IsModifiedT0` — True if `T0` is not zero.
- `bool IsModifiedLineFit` — True if `T1` or `T2` is not zero.
- `bool IsModifiedSensitivity` — True if `Sensitivity` differs from `SelectedChannel.Sensitivity`.
- `bool IsModifiedFilter` — True if `SelectedFilter` differs from the channel's current software filter.
- `bool IsModifiedDataFlag` — True if `SelectedDataFlag` differs from `SelectedChannel.DataFlag`.
- `bool IsModified` — Aggregate flag indicating any modification exists and `SelectedChannel` is non-null.

**Control Enable Properties:**
- `bool EnableSensitivityControl` — Controls UI sensitivity control visibility.
- `bool EnableLineFitControl` — Controls UI line fit control visibility.
- `bool EnableEUOffsetControl` — Controls UI EU offset control visibility.
- `bool EnableEUMultiplierControl` — Controls UI EU multiplier control visibility.
- `bool EnableFilterControl` — Controls UI filter control visibility.
- `bool EnableDescriptionControl` — Controls UI description control visibility.
- `bool IsDataFlagEnabled` — Controls UI data flag control visibility.
- `bool IsT0Enabled` — Controls UI T0 control visibility.
- `bool IsT0ModeTestOnly` — When true, forces `T0Mode` to `T0Mode.Test`.

**Other Properties:**
- `ITestModificationViewModel Parent` — Reference to parent view model.
- `bool IsSaved` — Read-only property (no setter visible in source).

**Methods:**
- `void OnPropertyChanged(string propertyName)` — Raises `PropertyChanged` event and recalculates `IsModified`.
- `bool ValidateT0()` — Validates T0 falls within the channel's dataset time range; returns true if `SelectedChannel` or `ParentModule` is null.

**Commands:**
- `DelegateCommand UpdateDatabaseCommand` — Executes `Parent.UpdateDatabaseMethod()`.

---

### TestModelManipulation.cs

#### `TestModelManipulation` Class
Static utility class for file-based test modification operations.

**Constants:**
- `double UNUSED_START_TIME = 0`
- `int UNUSED_DATA_COLLECTION_LENGTH = 0`
- `string BackupHeaderExtension = ".header.bak"` (private)
- `string BackupFileExtension = ".bak"` (private)

**Public Methods:**

- `static void UndoAllModification(ITestModificationModel model)` — Reverts all modifications by restoring `.dts` and all binary channel files from backups. Publishes `ChannelsModificationNotification`, `RefreshTestRequestEvent`, and `TestModificationEvent`.

- `static bool BackupExists(ITestModificationModel model)` — Returns true if either `.dts.bak` or `.chn.bak` backup files exist for the model's selected channel.

- `static void BackupChannelIfNeeded(Test.Module.Channel testModuleChannel, bool headerOnly)` — Creates backup of channel binary file. If `headerOnly` is true, backs up only the header portion; otherwise backs up the entire file.

- `static bool SaveModification(ITestModificationModel model, bool useISOCodeFilterMapping, bool bUseZeroForUnfiltered)` — Persists all modifications to disk. Returns true on success. Handles T0 (Test and DAS modes), line fit, filter, sensitivity, EU multiplier/offset, description, and data flag modifications.

- `static bool SaveModificationDataFlag(ITestModificationModel model)` — Saves only data flag modifications to disk.

- `static void ApplyLineFit(ITestModificationModel model, Test.Module.Channel channel)` — Applies linear interpolation between `T1` and `T2` sample indices on the channel's ADC data.

- `static void PreviewLineFit(ITestModificationModel model)` — Publishes `ChannelsModificationLineFitNotification` with calculated start/end indices without modifying disk.

- `static void UndoModification(ITestModificationModel model)` — Re-populates model from channel and publishes `ChannelsModificationNotification`.

- `static void PopulateFromChannel(ITestModificationModel model)` — Initializes model properties from `SelectedChannel` values.

---

## 3. Invariants

1. **Backup File Semantics**: Backup files (`.bak` and `.header.bak`) represent the *original* unmodified files. Once a backup exists, it is never overwritten by subsequent modifications—this preserves the ability to revert to the original state.

2. **IsModified Aggregation**: `IsModified` is true if and only if at least one `IsModified*` property is true AND `SelectedChannel` is non-null.

3. **T0Mode Restriction**: When `IsT0ModeTestOnly` is true, `T0Mode` setter forces the value to `T0Mode.Test` regardless of the input value.

4. **Calibration Property Dependencies**: `CalSensitivity`, `ProportionalToExcitation`, `NonLinear`, `ShowSensorCal`, `CalDate`, and `ModifyDate` all depend on `Cal` being non-null; they return default values (`false`, `NaN`, empty string) when `Cal` is null.

5. **Line Fit Index Ordering**: In `ApplyLineFit`, if `startIndex > endIndex`, the values are swapped before processing.

6. **T0 Validation Range**: `ValidateT0()` returns `true` (valid) if `SelectedChannel` or `ParentModule` is null, treating missing data as "no constraint."

---

## 4. Dependencies

### This Module Depends On:
- `DTS.Common` — Core utilities and interfaces
- `DTS.Common.Classes.Sensors` — Sensor-related classes
- `DTS.Common.Enums.Sensors` — Sensor enumerations including `DataFlag`, `T0Mode`
- `DTS.Common.Interface` — Core interfaces including `ITestChannel`
- `DTS.Common.Interface.Sensors` — Sensor interfaces including `ISensorCalDbRecord`, `ISensorDbRecord`
- `DTS.Common.Interface.Sensors.SoftwareFilters` — `IFilterClass`, `FilterClass`, `FilterClassType`
- `DTS.Common.Events` — Event types including `TestModificationEvent`, `TestModificationArgs`, `ChannelsModificationNotification`, `RefreshTestRequestEvent`, `ChannelsModificationLineFitNotification`, `LineFitArgs`
- `DTS.Common.Settings` — `SettingsDB` for global configuration values
- `DTS.Common.Utilities.Logging` — `APILogger`
- `DTS.Common.ISO` — `IsoCode` class
- `DTS.Serialization` — Serialization utilities including `SliceRaw.File`
- `DTS.SensorDB` — Sensor database interfaces
- `Prism.Commands` — `DelegateCommand`
- `Prism.Ioc` — `ContainerLocator`
- `Prism.Events` — `IEventAggregator`

### What Depends On This Module:
- Not determinable from the provided source files alone.

---

## 5. Gotchas

1. **Namespace Mismatch**: `TestModificationModel.cs` is declared in namespace `DTS.Viewer.ChartOptions.Model` despite residing in `DTS.Viewer.TestModification/Model/`. This may cause confusion when locating the class.

2. **ReSharper Suppressions**: The `TestModificationModel.cs` file contains multiple ReSharper suppressions (`InconsistentNaming`, `RedundantDefaultMemberInitializer`, `CheckNamespace`, `UnassignedGetOnlyAutoProperty`), suggesting known code style deviations.

3. **IsSaved Property Never Set**: The `IsSaved` property has a getter but no visible setter or initialization in the provided source, making its purpose unclear.

4. **Backup Strategy Complexity**: Binary channels can be backed up in two ways (header-only vs. full file). The `BackupChannelIfNeeded` method handles conversion between these modes, but developers should be aware that a header backup may be promoted to a full backup if subsequent modifications require it.

5. **T0 DAS Mode Scope**: When `T0Mode.DAS` is used, T0 changes are applied to all channels on the same DAS (matching `BaseSerialNumber`), not just the selected channel. This is a broader scope than might be expected.

6. **Line Fit Overwrites Data**: `ApplyLineFit` permanently replaces ADC data between T1 and T2 with linearly interpolated values. There is no undo mechanism specific to line fit beyond the full file restore.

7. **File Encoding Assumption**: `WriteDTSFileChanges` forces UTF-16 encoding for `.dts` files. The code catches exceptions and falls back to `Encoding.Default`, but this fallback could produce files incompatible with other consumers.

8. **Thread.Sleep in File Writing**: `WriteDTSFileChanges` includes a 10ms `Thread.Sleep()` after writing, suggesting a timing-related workaround for file system operations.