ReSharper DevGuide

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Gold Files

ReSharper’s test framework typically takes an input file, adds it as source file to an in-memory project, runs a process on it, such as inspections or code completion, and records the output in a temporary text file. This .tmp file is then compared to a .gold file, which contains the expected output. If they match, the test passes. If they don’t, the test fails.

The input file typically lives in the same folder under the test\data folder as the .gold file. The input file and the gold file should both be committed to source control. The .tmp file should not be committed, as it represents a failing test.

The contents of the gold file depends very much on the test. For example, gold files for code completion tests will be a list of items in the code completion list, while inspections will be a copy of the source file annotated with location and text of highlights. Details of the contents of gold files can be found throughout this guide, in the specific sections on testing a particular feature.

Input files

The input file typically lives in the same test\data sub-folder as the .gold file. Exactly what the input file is depends on the test, but mostly, it is a source file, such as .cs, .js, .html, etc. However, it can also be a compiled assembly, i.e. a .dll file.

Depending on the type of the file, it can be handled in different ways. It can be added as a source file to the in-memory project that the test environment creates, and the test will run some process over that file, such as running inspections, or invoking code completion. An assembly could be added as a reference to the in-memory project, and the test might perform metadata analysis (like Reflection) or decompilation, and put the output of that process to the .tmp file.

Special tokens

Creating gold files

To initially make a test pass, a known good gold file is required. The easiest way to create this is to run the test without a .gold file - which will cause it to fail. The resulting .tmp file should then be manually examined to see if it is the correct output for the test. If it is, it should be renamed to .gold.

Working with failures

When a test fails, ReSharper’s test framework adds extra information into the Data dictionary of the exception that the failing test throws. This data provides extra context about the test, and is rendered as part of the test failure message in the unit test runner. The following fields are added:

Field name Contents
GoldFile The path to the .gold file. This is rendered as a clickable file:// url that will open Windows Explorer with the .gold file selected.
TempFile The path to the .tmp file. This is rendered as a clickable file:// url that will open Windows Explorer with the .tmp file selected.
Cmd A clickable file:// url that will open a command prompt to the test\data sub-folder that contains the .gold or .tmp file.
Directory A plain text string that contains the sub-folder under test\data that contains the .gold or .tmp file.
Diff A diff between the .gold and .tmp files.
CopyToGold A clickable file:// url that will execute a .bat file that’s been created in the %TEMP% folder. The batch file will copy the .tmp file to the .gold file. This field is added when the .gold file doesn’t already exist.
UpdateGold A clickable file:// url that will execute a .bat file that’s been created in the %TEMP% folder. The batch file will copy the .tmp file over an existing .gold file. This should be used only once the differences between the existing .gold and the .tmp file have been examined and found to be correct.
ComparisonFile    A clickable file:// url that will execute a .bat file that’s been created in the %TEMP% folder. This batch file will open a visual diff tool to show the differences between the .tmp file and the .gold file. See below for more details.
GoldLine Can contain the first line of the .gold file that does not match against a new .tmp file. This is only used by certain tests.
TestLine Can contain the first line of the .tmp file that does not match against a .gold file. This is only used by certain tests.
LineNumber Can contain the line number of the first line in both the .tmp and .gold file that does not match. This is only used by certain tests.

Visual diff tools

When a test fails, the ComparisonFile field is added to the failing test’s exception’s Data dictionary. This field contains a clickable file:// url that will execute a .bat file that’s been saved in the %TEMP% folder. This batch file is as follows:

By default, it will launch the KDiff3 diff tool, passing in the parameters to display the .tmp and .gold files side by side. This can be overridden by defining the %DIFF% and %DIFF_PARAMETERS% environment variables.

The %DIFF% environment variable should be defined to the command needed to start the diff tool. This can be a fully qualified path, or just the executable name if it’s already on the path.

The %DIFF_PARAMETER% environment variable specifies the command line for the diff tool. The batch file will substitute the .temp and .gold names and full file paths for specific placeholders:

Placeholder Value
$plabel1 File name of the .tmp file.
$clabel File name of the .gold file.
$parent Full path to the .tmp file.
$child Full path to the .gold file.

For example, to use SourceGear DiffMerge as the diff tool, you can set:

Environment variable    Value
DIFF sgdm
DIFF_PARAMETERS /t1="$plabel1" /t2="$clabel" $parent $child
Last modified: 10 July 2017