Added test fixtures and removed the IsEmpty check

client/config/config.go

@@ -445,23 +445,6 @@ func (c *ClientTemplateConfig) Merge(b *ClientTemplateConfig) *ClientTemplateCon
 	return &result
 }
 
-func (c *ClientTemplateConfig) IsEmpty() bool {
-	if c == nil {
-		return true
-	}
-
-	return !c.DisableSandbox &&
-		len(c.FunctionDenylist) == 0 &&
-		len(c.FunctionBlacklist) == 0 &&
-		c.BlockQueryWaitTime == nil &&
-		c.BlockQueryWaitTimeHCL == "" &&
-		c.MaxStale == nil &&
-		c.MaxStaleHCL == "" &&
-		c.Wait.IsEmpty() &&
-		c.ConsulRetry.IsEmpty() &&
-		c.VaultRetry.IsEmpty()
-}
-
 // WaitConfig is mirrored from templateconfig.WaitConfig because we need to handle
 // the HCL conversion which happens in agent.ParseConfigFile
 // NOTE: Since Consul Template requires pointers, this type uses pointers to fields

command/agent/config_parse.go

@@ -259,8 +259,4 @@ func finalizeClientTemplateConfig(config *Config) {
 	if config.Client.TemplateConfig.VaultRetry.IsEmpty() {
 		config.Client.TemplateConfig.VaultRetry = nil
 	}
-
-	if config.Client.TemplateConfig.IsEmpty() {
-		config.Client.TemplateConfig = nil
-	}
 }

command/agent/config_parse_test.go

@@ -860,3 +860,56 @@ func permutations(arr []string) [][]string {
 	helper(arr, len(arr))
 	return res
 }
+
+func TestConfig_Parse_Client_TemplateConfig_FunctionDenylist(t *testing.T) {
+	t.Parallel()
+
+	defaultFunctionDenyList := DefaultConfig().Client.TemplateConfig.FunctionDenylist
+
+	cases := []struct {
+		File     string
+		Expected []string
+	}{
+		{
+			"client_with_function_denylist.hcl",
+			[]string{"foo"},
+		},
+		{
+			"client_with_function_denylist_empty.hcl",
+			nil,
+		},
+		{
+			"client_with_function_denylist_empty_string.hcl",
+			nil,
+		},
+		{
+			"client_with_function_denylist_nil.hcl",
+			defaultFunctionDenyList,
+		},
+		{
+			"client_with_empty_template.hcl",
+			defaultFunctionDenyList,
+		},
+		{
+			"minimal_client.hcl",
+			defaultFunctionDenyList,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.File, func(t *testing.T) {
+			path, err := filepath.Abs(filepath.Join("./test-resources", tc.File))
+			require.NoError(t, err)
+
+			parsed, err := ParseConfigFile(path)
+			require.NoError(t, err)
+
+			var actual []string
+			if tc.Expected != nil {
+				actual = parsed.Client.TemplateConfig.FunctionDenylist
+			}
+
+			require.EqualValues(t, tc.Expected, actual)
+		})
+	}
+}

command/agent/test-resources/client_with_empty_template.hcl

@@ -0,0 +1,6 @@
+client {
+  enabled = true
+
+  template {
+  }
+}

command/agent/test-resources/client_with_function_denylist.hcl

@@ -0,0 +1,7 @@
+client {
+  enabled = true
+
+  template {
+    function_denylist    = ["foo"]
+  }
+}

command/agent/test-resources/client_with_function_denylist_empty.hcl

@@ -0,0 +1,8 @@
+client {
+  enabled = true
+
+  template {
+    disable_file_sandbox = true
+    function_denylist    = []
+  }
+}

command/agent/test-resources/client_with_function_denylist_empty_string.hcl

@@ -0,0 +1,8 @@
+client {
+  enabled = true
+
+  template {
+    disable_file_sandbox = true
+    function_denylist    = [""]
+  }
+}

command/agent/test-resources/client_with_function_denylist_nil.hcl

@@ -0,0 +1,7 @@
+client {
+  enabled = true
+
+  template {
+    disable_file_sandbox = true
+  }
+}