fix: correct error message for prefix/suffix of empty strings

[vbreuss]

This PR fixes error message formatting for string prefix and suffix assertions when dealing with empty strings. The changes ensure that empty strings are properly handled in error messages to avoid displaying confusing contextual information.

Key changes:

• Updates error message logic to use string.IsNullOrEmpty() instead of null-only checks
• Adds conditional context display to prevent showing "Actual" context for null/empty strings
• Includes test coverage for empty string scenarios in both StartsWith and EndsWith assertions

[Copilot]

Pull Request Overview

This PR fixes error message formatting for string prefix and suffix assertions when dealing with empty strings. The changes ensure that empty strings are properly handled in error messages to avoid displaying confusing contextual information.

• Updates error message logic to use string.IsNullOrEmpty() instead of null-only checks
• Adds conditional context display to prevent showing "Actual" context for null/whitespace strings
• Includes test coverage for empty string scenarios in both StartsWith and EndsWith assertions

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
ThatString.StartsWith.Tests.cs	Adds test case for empty string input to verify proper error message formatting
ThatString.EndsWith.Tests.cs	Adds test case for empty string input to verify proper error message formatting
ThatString.IsEqualTo.cs	Conditionally adds "Actual" context only for non-null/non-whitespace strings
StringEqualityOptions.SuffixMatchType.cs	Updates null check to include empty strings for better error message handling
StringEqualityOptions.PrefixMatchType.cs	Updates null check to include empty strings for better error message handling

[github-actions]

🚀 Benchmark Results

Details

BenchmarkDotNet v0.14.0, Ubuntu 24.04.3 LTS (Noble Numbat)

AMD EPYC 7763, 1 CPU, 4 logical and 2 physical cores

.NET SDK 8.0.414

[Host] : .NET 8.0.20 (8.0.2025.41914), X64 RyuJIT AVX2
Job=InProcess  Toolchain=InProcessEmitToolchain  IterationCount=15

LaunchCount=1  WarmupCount=10

Method	Mean	Error	StdDev	Gen0	Gen1	Allocated
Bool_aweXpect	206.6 ns	0.90 ns	0.75 ns	0.0300	-	504 B
Bool_FluentAssertions	240.8 ns	0.69 ns	0.61 ns	0.0567	-	952 B
Bool_TUnit	859.1 ns	3.32 ns	3.11 ns	0.1431	-	2408 B
Equivalency_aweXpect	312,041.0 ns	1,126.42 ns	940.61 ns	20.0195	0.9766	335556 B
Equivalency_FluentAssertions	2,201,947.5 ns	4,083.46 ns	3,409.87 ns	273.4375	46.8750	4584416 B
Equivalency_TUnit	662,501.5 ns	1,310.68 ns	1,161.89 ns	51.7578	2.9297	880545 B
Int_GreaterThan_aweXpect	243.3 ns	0.64 ns	0.60 ns	0.0486	-	816 B
Int_GreaterThan_FluentAssertions	240.4 ns	1.34 ns	1.26 ns	0.0730	-	1224 B
Int_GreaterThan_TUnit	1,180.6 ns	3.11 ns	2.91 ns	0.1774	-	2984 B
ItemsCount_AtLeast_aweXpect	471.4 ns	1.51 ns	1.34 ns	0.0868	-	1464 B
ItemsCount_AtLeast_FluentAssertions	476.2 ns	2.25 ns	2.10 ns	0.1197	-	2008 B
ItemsCount_AtLeast_TUnit	23,403.8 ns	38.48 ns	35.99 ns	1.6174	-	27480 B
String_aweXpect	458.8 ns	0.93 ns	0.77 ns	0.0734	-	1232 B
String_FluentAssertions	453.9 ns	0.65 ns	0.51 ns	0.1292	-	2168 B
String_TUnit	1,180.4 ns	5.70 ns	5.05 ns	0.1831	-	3072 B
StringArray_aweXpect	1,912.0 ns	5.40 ns	4.79 ns	0.1717	-	2888 B
StringArray_FluentAssertions	1,260.9 ns	6.31 ns	5.90 ns	0.2480	-	4152 B
StringArray_TUnit	3,186.4 ns	5.59 ns	5.22 ns	0.3128	-	5296 B
StringArrayInAnyOrder_aweXpect	2,431.3 ns	5.44 ns	4.82 ns	0.1831	-	3080 B
StringArrayInAnyOrder_FluentAssertions	147,656.1 ns	1,137.55 ns	1,008.41 ns	3.4180	-	63787 B
StringArrayInAnyOrder_TUnit	3,746.1 ns	15.47 ns	14.47 ns	0.3853	-	6488 B

[github-actions]

👽 Mutation Results

aweXpect

Details

File	Score	Killed	Survived	Timeout	No Coverage	Ignored	Compile Errors	Total Detected	Total Undetected	Total Mutants
That/Strings/ThatString.IsEqualTo.cs	92.86%	13	1	0	0	2	4	13	1	20

The final mutation score is 92.86%

Coverage Thresholds: high:80 low:60 break:0

aweXpect.Core

Details

File	Score	Killed	Survived	Timeout	No Coverage	Ignored	Compile Errors	Total Detected	Total Undetected	Total Mutants
Options/StringEqualityOptions.PrefixMatchType.cs	93.10%	54	3	0	1	15	8	54	4	81
Options/StringEqualityOptions.SuffixMatchType.cs	63.08%	41	3	0	21	16	8	41	24	89

The final mutation score is 77.24%

Coverage Thresholds: high:80 low:60 break:0

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
2 Accepted issues

Measures
0 Security Hotspots
86.7% Coverage on New Code
4.7% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Test Results

    14 files   - 24      14 suites   - 24   5m 21s ⏱️ + 1m 8s
17 866 tests  - 25  17 861 ✅  - 27   5 💤 +2  0 ❌ ±0 
50 265 runs   - 66  50 254 ✅  - 72  11 💤 +6  0 ❌ ±0 

Results for commit 5774d8e. ± Comparison against base commit 07fdc9d.

This pull request removes 1561 and adds 1536 tests. Note that renamed tests count towards both.

aweXpect.Core.Tests.Core.Exceptions.FailExceptionTests ‑ Message_ShouldBeSet(message: "message2e332be1-fb2b-4ab2-a33f-d5307b9873a4")
aweXpect.Core.Tests.Core.Exceptions.FailExceptionTests ‑ Message_ShouldBeSet(message: "message4e5364d5-ea0f-4699-ba6a-22689cd09a59")
aweXpect.Core.Tests.Core.Exceptions.FailExceptionTests ‑ Message_ShouldBeSet(message: "messagea65ddd09-b7d2-4610-b7f0-d28956466ed8")
aweXpect.Core.Tests.Core.Exceptions.SkipExceptionTests ‑ Message_ShouldBeSet(message: "message14908bee-2734-461c-a07e-ab917e98e25f")
aweXpect.Core.Tests.Core.Exceptions.SkipExceptionTests ‑ Message_ShouldBeSet(message: "message1c325cc8-772f-4886-aa5f-07e0a5b0b507")
aweXpect.Core.Tests.Core.Exceptions.SkipExceptionTests ‑ Message_ShouldBeSet(message: "message91bc7459-4c26-443e-b02a-87715cfa71e3")
aweXpect.Core.Tests.FailTests ‑ Test_ShouldThrowException(reason: "reasona614ed03-a56f-4ef6-8194-8c03655d2827")
aweXpect.Core.Tests.FailTests ‑ Test_ShouldThrowException(reason: "reasond7dffcb9-e767-4880-a019-c77b22d9835e")
aweXpect.Core.Tests.FailTests ‑ Test_ShouldThrowException(reason: "reasonf66aba6c-d6b6-4a75-b77f-3922938379b8")
aweXpect.Core.Tests.FailTests ‑ Unless_ShouldThrowException(condition: False, reason: "reason2e652783-6734-42e2-a80e-7b49a66e3fff")
…

aweXpect.Core.Tests.Core.Exceptions.FailExceptionTests ‑ Message_ShouldBeSet(message: "message52d363a6-6646-407b-b63c-14b1f0fc8d90")
aweXpect.Core.Tests.Core.Exceptions.FailExceptionTests ‑ Message_ShouldBeSet(message: "message5be68e6d-71c3-44f3-80b0-5333da0ed271")
aweXpect.Core.Tests.Core.Exceptions.FailExceptionTests ‑ Message_ShouldBeSet(message: "messagef8801964-0dc3-4dba-8268-5de1ed9acf27")
aweXpect.Core.Tests.Core.Exceptions.SkipExceptionTests ‑ Message_ShouldBeSet(message: "message26290210-c51e-44e1-a3a5-8f4e7974e941")
aweXpect.Core.Tests.Core.Exceptions.SkipExceptionTests ‑ Message_ShouldBeSet(message: "messageaa204ca2-b0c8-49fa-9bac-1cce2485e9b9")
aweXpect.Core.Tests.Core.Exceptions.SkipExceptionTests ‑ Message_ShouldBeSet(message: "messageb5949639-8b8a-4689-a837-bb787d06f834")
aweXpect.Core.Tests.FailTests ‑ Test_ShouldThrowException(reason: "reason57078382-df5f-4844-bc21-d9cf38d2752b")
aweXpect.Core.Tests.FailTests ‑ Test_ShouldThrowException(reason: "reasonac2e3446-85b7-4aaf-9db5-107be5856182")
aweXpect.Core.Tests.FailTests ‑ Test_ShouldThrowException(reason: "reasond21c6764-7c24-4418-a56a-fc28642658ee")
aweXpect.Core.Tests.FailTests ‑ Unless_ShouldThrowException(condition: False, reason: "reason6cc91d87-a5ac-4b92-afd4-1eeee6815fcd")
…

[github-actions]

This is addressed in release v2.25.0.