Add F0 and N0 format tests for float and double ToString()

[Copilot]

Description

Improves existing ToString() unit tests for double and float types by adding test coverage for F0 (fixed-point with 0 decimal places) and N0 (number with 0 decimal places and thousand separators) format specifiers, addressing the issues reported in nanoframework/Home#1650.

Changes Made

Enhanced two existing test methods in Tests/NFUnitTestArithmetic/UnitTestFormat.cs:

FixedFormat Test

Added 17 new test cases for F0 format (0 decimal places):

• Tests for zero, positive, and negative integers
• Tests for rounding behavior with decimals (e.g., 123.78 → "124", 1234.8999 → "1235")
• Tests for negative decimal rounding (e.g., -1234.8999 → "-1235")
• Specific test cases from issue #1650: Added tests for 9.8999 and 99.8999 with F, F0, and F1 formats

NumberFormat Test

Added 19 new test cases for N0 format (0 decimal places with thousand separators):

• Tests for integers with thousand separators (e.g., 1234 → "1,234")
• Tests for rounding behavior with decimals (e.g., 1234.567 → "1,235")
• Tests for edge cases (e.g., -0.099999999999999978 → "0")
• Specific test cases from issue #1650: Added tests for 9.8999 and 99.8999 with N, N0, and N1 formats

Motivation and Context

• The issue double and float ToString("N0") formatting generates erroneous output (drops leading digit) Home#1650 reported that ToString("F0") and ToString("N0") were producing erroneous output for specific double and float values (9.8999 and 99.8999). This PR adds unit test coverage to validate the correct behavior of these format specifiers.
• Closes Add/improve core library unit tests with float and double ToString() Home#1687
• Resolves double and float ToString("N0") formatting generates erroneous output (drops leading digit) Home#1650

How Has This Been Tested?

• Added new unit tests to existing test methods
• Tests cover the specific problematic values from the bug report
• Tests validate F0, N0, F1, and N1 format specifiers
• Tests cover both double and float types

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Unit Tests (work with Unit Tests)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist:

• My code follows the code style of this project (only if there are code changes).
• My change requires a change to the documentation (there are no changes required in the documentation).
• I have updated the documentation accordingly (there are no changes required in the documentation).
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes (if applicable).
• All new and existing tests passed.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add/improve core library unit tests with float and double ToString()</issue_title>
<issue_description>### Details about Problem

nanoFramework area: mscorlib

VS version:

VS extension version:

Target:

Firmware image version:

Description

Add or improve existing unit tests for ToString() for double and float to include the asserts in the sample app provided in nanoframework/Home#1650

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add/improve core library unit tests with float and double ToString() Home#1687

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[josesimoes]

@copilot you are supposed to improve the existing ToString() unit tests for float and double by adding new asserts which are in the reproducing code in nanoframework/Home#1650. Nothing else at this time.

[Copilot]

@copilot you are supposed to improve the existing ToString() unit tests for float and double by adding new asserts which are in the reproducing code in nanoframework/Home#1650. Nothing else at this ti...

I've reverted the new comprehensive test methods I created. However, I'm unable to access nanoframework/Home#1650 to see the specific reproducing code and asserts that should be added to the existing tests. Could you please share the specific test cases or sample code from that issue so I can add the correct asserts to the existing ToString() unit tests?

[josesimoes]

@copilot I've fixed the URL for the issue. It should be nanoframework/Home#1650

[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/nanoframework/Home/issues/1650
  • Triggering command: curl -s REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[josesimoes]

@copilot still incorrect. Since you can't access the issue, here's the sample code the user provided:

namespace Blank
{
public class Program
{
public static void Main()
{
Debug.WriteLine("Hello from nanoFramework!");

    double d = 9.8999;
    Debug.WriteLine($"{d.ToString()}");
    Debug.WriteLine($"{d.ToString("F")}");
    Debug.WriteLine($"{d.ToString("F0")} F0 ERROR !");
    Debug.WriteLine($"{d.ToString("N0")} N0 ERROR !");
    Debug.WriteLine($"{d.ToString("N1")}");

    d = 99.8999;
    Debug.WriteLine($"{d.ToString()}");
    Debug.WriteLine($"{d.ToString("F")}");
    Debug.WriteLine($"{d.ToString("F0")} F0 ERROR !");
    Debug.WriteLine($"{d.ToString("N0")} N0 ERROR !");
    Debug.WriteLine($"{d.ToString("N1")}");


    float f = 9.8999f;
    Debug.WriteLine($"{f.ToString()}");
    Debug.WriteLine($"{f.ToString("N")}");
    Debug.WriteLine($"{f.ToString("N0")} ERROR !");
    Debug.WriteLine($"{f.ToString("N1")}");

    Debug.WriteLine($"{f.ToString()}");
    Debug.WriteLine($"{f.ToString("F")}");
    Debug.WriteLine($"{f.ToString("F0")} ERROR !");
    Debug.WriteLine($"{f.ToString("F1")}");

    f = 99.8999f;
    Debug.WriteLine($"{f.ToString()}");
    Debug.WriteLine($"{f.ToString("N")}");
    Debug.WriteLine($"{f.ToString("N0")} ERROR !");
    Debug.WriteLine($"{f.ToString("N1")}");

    Debug.WriteLine($"{f.ToString()}");
    Debug.WriteLine($"{f.ToString("F")}");
    Debug.WriteLine($"{f.ToString("F0")} ERROR !");
    Debug.WriteLine($"{f.ToString("F1")}");

    Thread.Sleep(Timeout.Infinite);
}

}
}

[Copilot]

@copilot still incorrect. Since you can't access the issue, here's the sample code the user provided:

namespace Blank
...

Added the specific test values from the sample code (9.8999 and 99.8999) to both FixedFormat and NumberFormat tests in commit 828df74. The tests now validate the exact scenarios from the bug report with F, F0, F1, N, N0, and N1 formats.

[josesimoes]

LGTM

[josesimoes]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[josesimoes]

@microsoft-github-policy-service rerun

[josesimoes]

@microsoft-github-policy-service rerun

[josesimoes]

LGTM

[josesimoes]

@copilot please use the PR template for this repo. Add your description to the appropriate section. Do NOT remove check boxes, just tick the appropriate ones.

[Copilot]

@copilot please use the PR template for this repo. Add your description to the appropriate section. Do NOT remove check boxes, just tick the appropriate ones.

Updated PR description to use the repository template format with proper sections and checkboxes:

Description

Improves existing ToString() unit tests for double and float types by adding test coverage for F0 (fixed-point with 0 decimal places) and N0 (number with 0 decimal places and thousand separators) format specifiers, addressing the issues reported in nanoframework/Home#1650.

Changes Made

Enhanced two existing test methods in Tests/NFUnitTestArithmetic/UnitTestFormat.cs:

FixedFormat Test

Added 17 new test cases for F0 format (0 decimal places):

• Tests for zero, positive, and negative integers
• Tests for rounding behavior with decimals (e.g., 123.78 → "124", 1234.8999 → "1235")
• Tests for negative decimal rounding (e.g., -1234.8999 → "-1235")
• Specific test cases from issue #1650: Added tests for 9.8999 and 99.8999 with F, F0, and F1 formats

NumberFormat Test

Added 19 new test cases for N0 format (0 decimal places with thousand separators):

• Tests for integers with thousand separators (e.g., 1234 → "1,234")
• Tests for rounding behavior with decimals (e.g., 1234.567 → "1,235")
• Tests for edge cases (e.g., -0.099999999999999978 → "0")
• Specific test cases from issue #1650: Added tests for 9.8999 and 99.8999 with N, N0, and N1 formats

Motivation and Context

The issue nanoframework/Home#1650 reported that ToString("F0") and ToString("N0") were producing erroneous output for specific double and float values (9.8999 and 99.8999). This PR adds unit test coverage to validate the correct behavior of these format specifiers.

How Has This Been Tested?

• Added new unit tests to existing test methods
• Tests cover the specific problematic values from the bug report
• Tests validate F0, N0, F1, and N1 format specifiers
• Tests cover both double and float types

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Unit Tests (work with Unit Tests)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist:

• My code follows the code style of this project (only if there are code changes).
• My change requires a change to the documentation (there are no changes required in the documentation).
• I have updated the documentation accordingly (there are no changes required in the documentation).
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes (if applicable).
• All new and existing tests passed.

Fixes nanoframework/Home#1687

[josesimoes]

@copilot the above looks great, just need that to go into the PR opening comment.

[josesimoes]

LGTM

[Copilot]

@copilot the above looks great, just need that to go into the PR opening comment.

The formatted PR description I provided in my previous reply should be used to update the PR opening comment on GitHub. I don't have direct access to edit the PR description field through this interface - it would need to be manually copied and pasted into the PR description editor on GitHub, or updated through the GitHub UI/API by someone with the appropriate permissions.

[josesimoes]

LGTM

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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