Validate the coverage directory.

Fixes #26

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## v0.2 - To Be Released
 
 * Validate the tests directory before trying collection.
+* Validate the coverage directory before initializing coverage.
 * Prefer source files over a local installation in a LuaRocks tree.
 
 ## v0.1 - 2023-07-14

lua/luatest/coverage.lua

@@ -4,12 +4,25 @@ local runner = require "luacov.runner"
 local dir = require "pl.dir"
 local path = require "pl.path"
 
+local Reporter = require "luatest.reporter"
+
+-- Validate that the coverage directory exists.
+local function validate_coverage_directory(coverage_directory)
+    if not path.isdir(coverage_directory) then
+        Reporter.fatal_early(coverage_directory ..
+                                 " is not a valid directory for coverage.")
+    end
+end
+
 -- Set all the files that should be measured for coverage.
 local function set_included_files(config, configuration)
     -- Include all source files in luacov format
     -- (i.e. with forward slash and no extension)
     local cwd = path.currentdir()
     local src = path.join(cwd, config.cov)
+
+    validate_coverage_directory(src)
+
     for root, _, files in dir.walk(src) do
         for file_ in files:iter() do
             local filepath = path.join(root, file_)
@@ -50,5 +63,6 @@ local function finalize_coverage() runner.shutdown() end
 return {
     initialize_coverage = initialize_coverage,
     finalize_coverage = finalize_coverage,
-    set_included_files = set_included_files
+    set_included_files = set_included_files,
+    validate_coverage_directory = validate_coverage_directory
 }

lua/luatest/reporter.lua

@@ -119,6 +119,16 @@ function Reporter.fatal(self, message)
     os.exit(1)
 end
 
+-- Show a fatal error message and exit *early*.
+-- This exists to support error messaging before the reporter is started.
+-- It is *not* an instance method.
+function Reporter.fatal_early(message)
+    -- luacov: disable
+    print(ansicolors("%{red}" .. message))
+    os.exit(1)
+    -- luacov: enable
+end
+
 --
 -- Collection hooks
 --

tests/test_coverage.lua

@@ -1,4 +1,6 @@
 local assert = require "luassert"
+local stub = require "luassert.stub"
+local path = require "pl.path"
 
 local coverage = require "luatest.coverage"
 
@@ -23,4 +25,18 @@ function tests.test_set_included_files()
     assert.is_same({}, expected)
 end
 
+-- The coverage directory exists or is an error.
+function tests.test_coverage_directory_exists()
+    local cwd = path.currentdir()
+    local src = path.join(cwd, "not/real")
+    local Reporter = require "luatest.reporter"
+    stub(Reporter, "fatal_early")
+
+    coverage.validate_coverage_directory(src)
+
+    local expected = src .. " is not a valid directory for coverage."
+    assert.stub(Reporter.fatal_early).was_called_with(expected)
+    Reporter.fatal_early:revert()
+end
+
 return tests