Based on the , Shouldly has ShouldMatchApproved() to do approval based testing. The main goal of Shouldly's approval testing is for it to be simple, intuitive and give great error messages.
To configure failed approvals to display a comparison of the approved and failed files, install the nuget package and confgure it as follows:
// In your test setup
ShouldlyConfiguration.ShouldMatchApprovedDefaults.ConfigureDiffEngine();
Approved File does not exist
When you first run a ShouldMatchApproved test, you will be presented with a diff viewer and a failing test.
var simpsonsQuote = "Hi Super Nintendo Chalmers";
simpsonsQuote.ShouldMatchApproved();
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Exception
To approve the changes run this command:
copy /Y "C:\PathToCode\shouldly\src\DocumentationExamples\ShouldMatchApprovedExamples.ApprovedFileDoesNotExist.received.txt" "C:\PathToCode\shouldly\src\DocumentationExamples\ShouldMatchApprovedExamples.ApprovedFileDoesNotExist.approved.txt"
----------------------------
Approval file C:\PathToCode\shouldly\src\DocumentationExamples\ShouldMatchApprovedExamples.ApprovedFileDoesNotExist.approved.txt
does not exist
Screenshot
Approved File does not match received
After you have approved the text, when it changes you get a different experience.
var simpsonsQuote = "Me fail english? That's unpossible";
simpsonsQuote.ShouldMatchApproved();
Exception
To approve the changes run this command:
copy /Y "C:\PathToCode\shouldly\src\DocumentationExamples\ShouldMatchApprovedExamples.ApprovedFileIsDifferent.received.txt" "C:\PathToCode\shouldly\src\DocumentationExamples\ShouldMatchApprovedExamples.ApprovedFileIsDifferent.approved.txt"
----------------------------
simpsonsQuote
should match approved with options: Ignoring line endings
"Hi Super Nintendo Chalmers"
but was
"Me fail english? That's unpossible"
difference
Difference | | | | | | | | | | | | | | | | | | | | |
| \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/
Index | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ...
Expected Value | H i \s S u p e r \s N i n t e n d o \s C h a ...
Actual Value | M e \s f a i l \s e n g l i s h ? \s T h a t ...
Expected Code | 72 105 32 83 117 112 101 114 32 78 105 110 116 101 110 100 111 32 67 104 97 ...
Actual Code | 77 101 32 102 97 105 108 32 101 110 103 108 105 115 104 63 32 84 104 97 116 ...
Difference | | | | | | | | | | | | | | | | | | | | | |
| \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/ \|/
Index | ... 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
Expected Value | ... e n d o \s C h a l m e r s
Actual Value | ... s h ? \s T h a t ' s \s u n p o s s i b l e
Expected Code | ... 101 110 100 111 32 67 104 97 108 109 101 114 115
Actual Code | ... 115 104 63 32 84 104 97 116 39 115 32 117 110 112 111 115 115 105 98 108 101
Screenshot
Options and customisation
While the defaults should work fine, often you need to customise things easily. ApprovalTests is highly configurable but the configuration is not always discoverable. Shouldly wants to make configuration simple and discoverable. This section covers the local customisations availble for a single ShouldMatchApproved call.
Defaults
The first thing to note is that by default Shouldly ignores line endings. This saves painful failures on the build server when git checks out the approved files with rather than \r which the received file has. You can opt out of this behaviour for a single call, or globally. For global defaults see the Configuration section.
var options = StringCompareShould.IgnoreCase | StringCompareShould.IgnoreLineEndings;
toVerify.ShouldMatchApproved(c => c.WithStringCompareOptions(options))
WithDiscriminator
By default the approved and received files are named ${MethodName}.approved.txt, WithDiscriminator allows you to discriminate multiple files, useful for data driven tests which can have multiple executions of a single method. For example
[Fact]
public void Simpsons()
{
toVerify.ShouldMatchApproved(c => c.WithDiscriminator("Bart"));
}
Will result in a approved file with the name Simpsons.Bart.approved.txt
Diff
toVerify.ShouldMatchApproved(c => c.Diff())
NoDiff
Prevents the diff viewer from opening up. Doing this you can use Shouldly's error messages to verify the changes then run the command in the exception message to approve the changes.
toVerify.ShouldMatchApproved(c => c.NoDiff())
WithFileExtension
Override the file extension of the approved/received files. The default is .txt.
By default shouldly will walk the stacktrace to find the first non-shouldly method (not including anonymous methods and compiler generated stuff like the async state machine) and use that method for the approval filename. I.e a test named MyTest will result in a received filename of MyTest.received.txt.
This setting tells shouldly to walk one more frame, this is really handy when you have created a utility function which calls ShouldMatchApproved.
[Fact]
public void MyTest()
{
SomeUtilityMethod("Foo");
}
void SomeUtilityMethod(string toApprove)
{
toApprove.ShouldMatchApproved(c => c.UseCallerLocation());
}
// -> MyTest.received.txt - without UseCallerLocation() the file would be called SomeUtilityMethod.received.txt
LocateTestMethodUsingAttribute
If you want to locate your test method using an attribute that is easy too!
Will turn Today is 01/01/2016 into Today is <date> in the received file.
Configuration
Changing default options
All of the instance based configuration can be changed globally through ShouldlyConfiguration.ShouldMatchApprovedDefaults. For example to make the default behaviour be line ending sensitive you can just run this before any tests execute ShouldlyConfiguration.ShouldMatchApprovedDefaults.DoNotIgnoreLineEndings()
Diff tools
// In your test setup
ShouldlyConfiguration.ShouldMatchApprovedDefaults.ConfigureDiffEngine();
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Opens the diff viewer if the files do not match. Requires the package to be installed.
Shouldly.DiffEngine uses for launching diff tools. Use the following to configure enable the diff viewer when not disabled within DiffEngine:
