Allow ModuleConfig.WithName("") to clear the module name (#1277)

We currently allow clearing other config with nil, such as FSConfig.
However, we missed a spot as internally we couldn't differentiate
between name never set, or explicitly set to empty. Now, when someone
sets the module name to empty, the name in the binary section is
ignored.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

config_test.go

@@ -100,29 +100,50 @@ func TestRuntimeConfig(t *testing.T) {
 
 func TestModuleConfig(t *testing.T) {
 	tests := []struct {
-		name     string
-		with     func(ModuleConfig) ModuleConfig
-		expected string
+		name          string
+		with          func(ModuleConfig) ModuleConfig
+		expectNameSet bool
+		expectedName  string
 	}{
+		{
+			name: "WithName default",
+			with: func(c ModuleConfig) ModuleConfig {
+				return c
+			},
+			expectNameSet: false,
+			expectedName:  "",
+		},
 		{
 			name: "WithName",
 			with: func(c ModuleConfig) ModuleConfig {
 				return c.WithName("wazero")
 			},
-			expected: "wazero",
+			expectNameSet: true,
+			expectedName:  "wazero",
 		},
 		{
 			name: "WithName empty",
 			with: func(c ModuleConfig) ModuleConfig {
 				return c.WithName("")
 			},
+			expectNameSet: true,
+			expectedName:  "",
 		},
 		{
 			name: "WithName twice",
 			with: func(c ModuleConfig) ModuleConfig {
 				return c.WithName("wazero").WithName("wa0")
 			},
-			expected: "wa0",
+			expectNameSet: true,
+			expectedName:  "wa0",
+		},
+		{
+			name: "WithName can clear",
+			with: func(c ModuleConfig) ModuleConfig {
+				return c.WithName("wazero").WithName("")
+			},
+			expectNameSet: true,
+			expectedName:  "",
 		},
 	}
 	for _, tt := range tests {
@@ -131,7 +152,8 @@ func TestModuleConfig(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			input := NewModuleConfig()
 			rc := tc.with(input)
-			require.Equal(t, tc.expected, rc.(*moduleConfig).name)
+			require.Equal(t, tc.expectNameSet, rc.(*moduleConfig).nameSet)
+			require.Equal(t, tc.expectedName, rc.(*moduleConfig).name)
 			// The source wasn't modified
 			require.Equal(t, NewModuleConfig(), input)
 		})