What causes "Negative value is not allowed here" in mockito/mockito?

Ensure the count passed to times() is >= 0; clamp or assert before use

mockito/mockito · error · MockitoException

Negative value is not allowed here

Error message

Negative value is not allowed here

What it means

Mockito's Times verification mode requires a non-negative invocation count. The Times constructor throws this MockitoException when given a negative number, since 'verify exactly -N times' is meaningless.

Source

Thrown at mockito-core/src/main/java/org/mockito/internal/verification/Times.java:26

import static org.mockito.internal.verification.checkers.NumberOfInvocationsChecker.checkNumberOfInvocations;

import java.util.List;

import org.mockito.exceptions.base.MockitoException;
import org.mockito.internal.verification.api.VerificationData;
import org.mockito.internal.verification.api.VerificationDataInOrder;
import org.mockito.internal.verification.api.VerificationInOrderMode;
import org.mockito.invocation.Invocation;
import org.mockito.invocation.MatchableInvocation;
import org.mockito.verification.VerificationMode;

public class Times implements VerificationInOrderMode, VerificationMode {

    final int wantedCount;

    public Times(int wantedNumberOfInvocations) {
        if (wantedNumberOfInvocations < 0) {
            throw new MockitoException("Negative value is not allowed here");
        }
        this.wantedCount = wantedNumberOfInvocations;
    }

    @Override
    public void verify(VerificationData data) {
        List<Invocation> invocations = data.getAllInvocations();
        MatchableInvocation wanted = data.getTarget();

        if (wantedCount > 0) {
            checkMissingInvocation(data.getAllInvocations(), data.getTarget());
        }
        checkNumberOfInvocations(invocations, wanted, wantedCount);
    }

    @Override
    public void verifyInOrder(VerificationDataInOrder data) {
        List<Invocation> allInvocations = data.getAllInvocations();

View on GitHub (pinned to 5a676bcd9e)

Solutions

Ensure the count passed to times() is >= 0; clamp or assert before use
Use never() for zero expected invocations instead of times(0)/negative values
Check the arithmetic producing the count (e.g. Math.max(0, expected))

Example fix

// before
verify(mock, times(items.size() - removed)); // can be negative
// after
verify(mock, times(Math.max(0, items.size() - removed)));

Defensive patterns

Strategy: validation

Validate before calling

int expected = computeCount();
if (expected < 0) throw new IllegalArgumentException("times() count must be >= 0, got " + expected);
verify(mock, times(expected));

Prevention

Clamp computed counts with Math.max(0, n)
Use never() for zero-invocation checks
Assert intermediate data sizes before deriving expected counts

When it happens

Trigger: Calling Mockito.times(-1) or verify(mock, times(negativeCount)) with a hardcoded negative or a computed count that went negative (e.g. list.size()-k when k > size).

Common situations: Computing expected counts from dynamic data (collections sizes, counters) that can go negative; typos in test constants; off-by-one arithmetic in parameterized tests.

Related errors

AI-assisted analysis of mockito/mockito@5a676bcd9e (2026-09-05). Data as JSON: /api/errors/a48a510cde60f3df. Report an issue: GitHub.