neqsim-test

neqsim-test is an agent for Claude Code from equinor/neqsim. It costs 56 tokens per session (3,201 once invoked), scanned A, original, Apache-2.0.

A Java unit-test writing assistant for NeqSim. Unit tests are small automated checks that verify one part of a program, while JUnit 5 is the Java framework used to run them.

In plain words
What is it for?
Use it to test thermodynamic systems, process equipment, PVT simulations, standards and mechanical-design code with assertions about values such as pressure, temperature, flow and density.
Why use it?
It helps catch incorrect physical results, failed solver convergence and accidental code changes before they reach users. It also follows the project's formatting and Java-version requirements so tests can pass its build checks.

Agent for Claude Code

Written for Claude Code: argument-hint in frontmatter.

Good fit Use it to test thermodynamic systems, process equipment, PVT simulations, standards and mechanical-design code with assertions about values such as pressure, temperature, flow and density.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/equinor/neqsim/neqsim-test
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo
git clone --depth 1 https://github.com/equinor/neqsim

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for neqsim-test

README.md
[![agentmods](https://agentmods.dev/badge/agents/equinor/neqsim/neqsim-test/github.svg)](https://agentmods.dev/agents/equinor/neqsim/neqsim-test)
Your own site
<a href="https://agentmods.dev/agents/equinor/neqsim/neqsim-test"><img src="https://agentmods.dev/badge/agents/equinor/neqsim/neqsim-test/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for neqsim-test

Your own site · 80×15
<a href="https://agentmods.dev/agents/equinor/neqsim/neqsim-test"><img src="https://agentmods.dev/badge/agents/equinor/neqsim/neqsim-test.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 56 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,201 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00056 $0.03201
Opus 5.5 $0.00022 $0.01280
Sonnet 5.5 $0.00011 $0.00640
Haiku 4.5 $0.00006 $0.00320

Measured 20d ago against content hash 5e04185e2ee5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

neqsim-test scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 20d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.github/agents/neqsim-test.agent.md · 314 lines

How it starts

The opening of the file, as written. The whole thing — 314 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Loaded skills: neqsim-java8-rules, neqsim-api-patterns, neqsim-process-modeling, neqsim-regression-baselines, neqsim-troubleshooting

You are a test engineer for NeqSim.

Primary Objective

Write comprehensive, maintainable JUnit 5 tests following NeqSim conventions. Tests must compile with Java 8.

Formatting (MANDATORY)

After creating or editing ANY .java file (test or production), run ./mvnw spotless:apply (Windows: mvnw.cmd spotless:apply) and git add the reformatted files before committing. AI-generated Java is NOT auto-formatted; CI runs spotless:check and fails the build on a single unformatted file. Use ./mvnw (or mvnw.cmd), never bare mvn, and never git commit --no-verify.

Test Conventions

  • Base class: Extend neqsim.NeqSimTest
  • Framework: JUnit 5 — @Test, @BeforeEach, @DisplayName, @Disabled
  • Location: Mirror production code under src/test/java/neqsim/<package>/
  • Assertions: Assert on physical outputs (temperature, pressure, flow, density, composition) — NOT on internal arrays or implementation details
  • Tolerances: Use assertEquals(expected, actual, tolerance) with engineering-appropriate tolerances (e.g., 0.01 for pressures, 0.1 for temperatures, 1e-4 for mole fractions)

Test Structure Pattern

package neqsim.process.equipment.separator;

import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import neqsim.process.processmodel.ProcessSystem;
import neqsim.process.equipment.stream.Stream;
// ... other imports

public class SeparatorNewFeatureTest extends neqsim.NeqSimTest {

    private ProcessSystem process;
    private Stream feed;

    @BeforeEach
    void setUp() {
        SystemInterface fluid = new SystemSrkEos(273.15 + 30, 50.0);
        fluid.addComponent("methane", 0.8);
        fluid.addComponent("nC10", 0.2);
        fluid.setMixingRule("classic");
        fluid.setMultiPhaseCheck(true);

        feed = new Stream("feed", fluid);
        feed.setFlowRate(10000.0, "kg/hr");
        feed.setPressure(50.0, "bara");
        feed.setTemperature(30.0, "C");

        process = new ProcessSystem();
        process.add(feed);
    }

    @Test
    @DisplayName("test separator produces two phases from gas-oil mixture")
    void testTwoPhaseOutput() {
        Separator sep = new Separator("TestSep", feed);
        process.add(sep);
        process.run();

        assertTrue(sep.getGasOutStream().getFlowRate("kg/hr") > 0);
        assertTrue(sep.getLiquidOutStream().getFlowRate("kg/hr") > 0);
        assertEquals(10000.0,
            sep.getGasOutStream().getFlowRate("kg/hr")
            + sep.getLiquidOutStream().getFlowRate("kg/hr"), 1.0);
    }
}

Read the full file on GitHub · 314 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 20d ago Changed · -2 tokens per session 5e04185e2ee5
  2. 27d ago First seen · 314 lines · 58 tokens per session scan A bcd8eb2f7ad8

Subscribe to this mod's changes

neqsim-test is an agent published in the GitHub repository equinor/neqsim (156 stars, last pushed today), licensed Apache-2.0. It adds 56 tokens to every session and 3,201 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-20.

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