E83001: code coverage below threshold

What went wrong

Your code coverage is below the required threshold (80%). Tests passed, but insufficient code paths were exercised.

Worked examples

Compilable examples demonstrating this error and the correct fix:

• ek9 -q 811 (How do coverage thresholds and exit codes work in EK9?)
• ek9 -q 206 (How do I measure test coverage in EK9?)

Coverage metrics

• Method Coverage: percentage of functions/methods called
• Line Coverage: percentage of source code lines executed
• Branch Coverage: percentage of if/else, switch, loops exercised

How to fix it

1. Check coverage report: `ek9 -t4 myfile.ek9` (detailed)
2. Add tests for uncovered methods
3. Test both branches of conditionals (true AND false)
4. Test exception paths: `assertThrows Exception in funcThatThrows()`
5. Test loop edge cases: empty, single, multiple items

Coverage files

.ek9/coverage-detail.json   // Uncovered items only
.ek9/coverage-verbose.json  // Complete breakdown

Common causes

• Missing tests for certain functions
• Only testing happy path (missing error/exception cases)
• Loop bodies never entered (empty collections)
• Dead code that cannot be reached

Examples

Every example is compiled by the EK9 compiler: the first fails exactly as captioned, the others fix it.

Fails with E83001: code coverage below threshold - reported by the test runner, not the compiler, when ek9 -t greeting.ek9 runs in this project.

bad/greeting.ek9

#!ek9
defines module error.e83001.bad

  defines function

    greeting() as pure
      -> name as String
      <- result as String: `Hello, ${name}`

    shout() as pure
      -> name as String
      <- result as String: greeting(name).upperCase()

    whisper() as pure
      -> name as String
      <- result as String: greeting(name).lowerCase()

    padded() as pure
      -> name as String
      <- result as String: ` ${greeting(name)} `

bad/dev/tests.ek9

#!ek9
defines module error.e83001.bad.tests

  references
    error.e83001.bad::greeting

  defines program

    @Test
    GreetingIsKept()
      assert greeting("EK9") == "Hello, EK9"

$ ek9 -t greeting.ek9
ℹ️ Found 1 test:
  1 assert (unit tests with assertions)

Executing 1 test...

✅ PASS error.e83001.bad.tests::GreetingIsKept [Assert] (nms)

Summary: 1 passed, 0 failed (1 total)
Types: 1 assert
Duration: nms

❌ E83001: Code coverage 25.0% is below required threshold 80%
   Methods:  25.0% (1/4)
   Lines:    25.0% (3/12)

   Uncovered items:
     3 method(s)
       • error.e83001.bad::shout (./greeting.ek9:10)
       • error.e83001.bad::whisper (./greeting.ek9:14)
       • error.e83001.bad::padded (./greeting.ek9:18)

   Use -t4 or -t5 for detailed coverage report.
ek9: coverage below the required threshold (exit 12)

Fixed: Every function has a test

good/greeting.ek9

#!ek9
defines module error.e83001.good

  defines function

    greeting() as pure
      -> name as String
      <- result as String: `Hello, ${name}`

    shout() as pure
      -> name as String
      <- result as String: greeting(name).upperCase()

    whisper() as pure
      -> name as String
      <- result as String: greeting(name).lowerCase()

    padded() as pure
      -> name as String
      <- result as String: ` ${greeting(name)} `

good/dev/tests.ek9

#!ek9
defines module error.e83001.good.tests

  references
    error.e83001.good::greeting
    error.e83001.good::padded
    error.e83001.good::shout
    error.e83001.good::whisper

  defines program

    @Test
    GreetingIsKept()
      assert greeting("EK9") == "Hello, EK9"

    @Test
    ShoutIsUpperCase()
      assert shout("EK9") == "HELLO, EK9"

    @Test
    WhisperIsLowerCase()
      assert whisper("EK9") == "hello, ek9"

    @Test
    PaddedHasSpaces()
      assert padded("EK9") == " Hello, EK9 "

$ ek9 -t greeting.ek9
ℹ️ Found 4 tests:
  4 assert (unit tests with assertions)

Executing 4 tests...

✅ PASS error.e83001.good.tests::GreetingIsKept [Assert] (nms)
✅ PASS error.e83001.good.tests::PaddedHasSpaces [Assert] (nms)
✅ PASS error.e83001.good.tests::ShoutIsUpperCase [Assert] (nms)
✅ PASS error.e83001.good.tests::WhisperIsLowerCase [Assert] (nms)

Summary: 4 passed, 0 failed (4 total)
Types: 4 assert
Duration: nms