Changed test code not reflected in coverage

[sverhoeven]

Description

Coverage report does not change after adding test and running test suite.

Expected behavior

After test run the coverage is changed with newly tested code covered.

Actual behavior

After test run the coverage is unchanged, leaving newly tested code uncovered.

Environment

Error happens in https://github.com/3D-e-Chem/molviewer-tsx/blob/2588004f600064964f471149c6cd8f6e14f083f0

node: v7.8.0
npm: 4.2.0
yarn:0.21.3

Reproducible Demo

0. Clone repo (https://github.com/3D-e-Chem/molviewer-tsx.git) + yarn install
1. Comment out test at https://github.com/3D-e-Chem/molviewer-tsx/blob/2588004f600064964f471149c6cd8f6e14f083f0/src/components/GLModel.spec.ts#L28-L32
2. Started with correct coverage in coverage/remapped directory.
3. Enable test again to increase the coverage then ran yarn test -- --coverage.
4. Afterwards the coverage report is unchanged.

Workaround: Before running test clearing coverage and jest cache by rm -r coverage/ /tmp/jest.

[sverhoeven]

Better workaround:

yarn test -- --coverage --no-cache -w 1

The --no-cache and -w 1 are used to force the ts-jest preprocessor and coverageprocessor to use the global cache var.