test: improve testing quality

conf.v

@@ -2,6 +2,7 @@ module conf
 
 import os
 import toml
+import datatypes { Set }
 
 // get_env_var tries to read the contents of the given environment variable. It
 // looks for either `${env.prefix}${field_name.to_upper()}` or
@@ -54,7 +55,7 @@ pub fn load<T>(conf LoadConfig) !T {
 
 	// This array allows us to determine later whether the variable is actually
 	// zero or just a null'ed struct field
-	mut has_value := map[string]bool{}
+	mut has_value := Set<string>{}
 
 	// Later, this could be read from an env var as well.
 	path := conf.default_path
@@ -77,7 +78,7 @@ pub fn load<T>(conf LoadConfig) !T {
 					//	$compile_error('Unsupported config struct field type detected.')
 				}
 
-				has_value[field.name] = true
+				has_value.add(field.name)
 			}
 		}
 	}
@@ -97,12 +98,31 @@ pub fn load<T>(conf LoadConfig) !T {
 				//	$compile_error('Unsupported config struct field type detected.')
 			}
 
-			has_value[field.name] = true
+			has_value.add(field.name)
 		}
 
-		if !(has_value[field.name] or { false }) {
+		// Finally, if there's no env var present either, we check whether the
+		// variable has a default value
+		if !has_value.exists(field.name) {
+			mut has_default := false
+
+			$if field.typ is string {
+				has_default = res.$(field.name) != ''
+			} $else $if field.typ is int {
+				has_default = res.$(field.name) != 0
+			}
+
+			if has_default {
+				has_value.add(field.name)
+			}
+		}
+
+        // If there's no value provided in any way, we notify the user with an
+        // error.
+		if !has_value.exists(field.name) {
 			return error("Missing config variable '$field.name' with no provided default. Either add it to the config file or provide it using an environment variable.")
 		}
 	}
+
 	return res
 }

string_test.v

@@ -0,0 +1,35 @@
+module conf
+
+struct SingleConf {
+	some_string string
+}
+
+struct SingleConfDefault {
+	some_string string = 'default'
+}
+
+fn test_string_present_no_default() {
+	conf := load<SingleConf>(default_path: 'test/string.toml')!
+	assert conf == SingleConf{
+		some_string: 'hi'
+	}
+}
+
+fn test_string_absent_no_default() {
+	conf := load<SingleConf>(default_path: 'test/empty.toml') or { return }
+	assert false
+}
+
+fn test_string_present_default() {
+	conf := load<SingleConfDefault>(default_path: 'test/string.toml')!
+	assert conf == SingleConfDefault{
+		some_string: 'hi'
+	}
+}
+
+fn test_string_absent_default() {
+	conf := load<SingleConfDefault>(default_path: 'test/empty.toml')!
+	assert conf == SingleConfDefault{
+		some_string: 'default'
+	}
+}

test/string.toml

@@ -0,0 +1 @@
+some_string = "hi"