fix: in toml config, only apply environment substitution to coverage settings. #1481

1 files changed, 47 insertions, 22 deletions

diff --git a/coverage/tomlconfig.py b/coverage/tomlconfig.py
index 148c34f8..0b5052b4 100644
--- a/coverage/tomlconfig.py
+++ b/coverage/tomlconfig.py
@@ -52,7 +52,6 @@ class TomlConfigParser:
         except OSError:
             return []
         if tomllib is not None:
-            toml_text = substitute_variables(toml_text, os.environ)
             try:
                 self.data = tomllib.loads(toml_text)
             except tomllib.TOMLDecodeError as err:
@@ -101,9 +100,21 @@ class TomlConfigParser:
         if data is None:
             raise configparser.NoSectionError(section)
         try:
-            return name, data[option]
+            value = data[option]
         except KeyError as exc:
             raise configparser.NoOptionError(option, name) from exc
+        return name, value
+
+    def _get_single(self, section, option):
+        """Get a single-valued option.
+
+        Performs environment substitution if the value is a string. Other types
+        will be converted later as needed.
+        """
+        name, value = self._get(section, option)
+        if isinstance(value, str):
+            value = substitute_variables(value, os.environ)
+        return name, value
 
     def has_option(self, section, option):
         _, data = self._get_section(section)
@@ -126,29 +137,45 @@ class TomlConfigParser:
         return data
 
     def get(self, section, option):
-        _, value = self._get(section, option)
+        _, value = self._get_single(section, option)
         return value
 
-    def _check_type(self, section, option, value, type_, type_desc):
-        if not isinstance(value, type_):
-            raise ValueError(
-                'Option {!r} in section {!r} is not {}: {!r}'
-                    .format(option, section, type_desc, value)
-            )
+    def _check_type(self, section, option, value, type_, converter, type_desc):
+        """Check that `value` has the type we want, converting if needed.
+
+        Returns the resulting value of the desired type.
+        """
+        if isinstance(value, type_):
+            return value
+        if isinstance(value, str) and converter is not None:
+            try:
+                return converter(value)
+            except Exception as e:
+                raise ValueError(
+                    f"Option [{section}]{option} couldn't convert to {type_desc}: {value!r}"
+                ) from e
+        raise ValueError(
+            f"Option [{section}]{option} is not {type_desc}: {value!r}"
+        )
 
     def getboolean(self, section, option):
-        name, value = self._get(section, option)
-        self._check_type(name, option, value, bool, "a boolean")
-        return value
+        name, value = self._get_single(section, option)
+        bool_strings = {"true": True, "false": False}
+        return self._check_type(name, option, value, bool, bool_strings.__getitem__, "a boolean")
 
-    def getlist(self, section, option):
+    def _get_list(self, section, option):
+        """Get a list of strings, substituting environment variables in the elements."""
         name, values = self._get(section, option)
-        self._check_type(name, option, values, list, "a list")
+        values = self._check_type(name, option, values, list, None, "a list")
+        values = [substitute_variables(value, os.environ) for value in values]
+        return name, values
+
+    def getlist(self, section, option):
+        _, values = self._get_list(section, option)
         return values
 
     def getregexlist(self, section, option):
-        name, values = self._get(section, option)
-        self._check_type(name, option, values, list, "a list")
+        name, values = self._get_list(section, option)
         for value in values:
             value = value.strip()
             try:
@@ -158,13 +185,11 @@ class TomlConfigParser:
         return values
 
     def getint(self, section, option):
-        name, value = self._get(section, option)
-        self._check_type(name, option, value, int, "an integer")
-        return value
+        name, value = self._get_single(section, option)
+        return self._check_type(name, option, value, int, int, "an integer")
 
     def getfloat(self, section, option):
-        name, value = self._get(section, option)
+        name, value = self._get_single(section, option)
         if isinstance(value, int):
             value = float(value)
-        self._check_type(name, option, value, float, "a float")
-        return value
+        return self._check_type(name, option, value, float, float, "a float")