support code block in code block

internal/terraform/plan.go

@@ -1,9 +1,11 @@
 package terraform
 
 import (
+	"bufio"
 	"encoding/json"
 	"fmt"
 	"io"
+	"regexp"
 	"strings"
 	"text/template"
 
@@ -31,9 +33,7 @@ const planTemplateBody = `### {{len .CreatedAddresses}} to add, {{len .UpdatedAd
 {{if .ResourceChanges -}}
 <details><summary>Change details</summary>
 {{ range .ResourceChanges }}
-{{codeFence}}diff
-# {{.ResourceChange.Type}}.{{.ResourceChange.Name}} {{.HeaderSuffix}}
-{{.GetUnifiedDiffString}}{{codeFence}}
+{{.GetUnifiedDiffString}}
 {{end}}
 </details>
 {{end}}`
@@ -69,8 +69,10 @@ func (r ResourceChangeData) GetUnifiedDiffString() (string, error) {
 	if err != nil {
 		return "", fmt.Errorf("failed to create diff: %w", err)
 	}
+	comment := fmt.Sprintf("# %s.%s %s", r.ResourceChange.Type, r.ResourceChange.Name, r.HeaderSuffix())
+	fence := r.codeFence(diffText)
 
-	return diffText, nil
+	return fence + "diff\n" + comment + "\n" + diffText + fence, nil
 }
 
 func (r ResourceChangeData) HeaderSuffix() string {
@@ -87,14 +89,23 @@ func (r ResourceChangeData) HeaderSuffix() string {
 	return ""
 }
 
-func (plan *PlanData) Render(w io.Writer) error {
-	funcMap := template.FuncMap{
-		"codeFence": func() string {
-			return "```"
-		},
+var codeFenceRegexp = regexp.MustCompile(`\s*(` + "`" + `{3,})`)
+
+func (r ResourceChangeData) codeFence(diffText string) string {
+	count := 3
+
+	scanner := bufio.NewScanner(strings.NewReader(diffText))
+	for scanner.Scan() {
+		values := codeFenceRegexp.FindStringSubmatch(scanner.Text())
+		if values != nil && len(values[1]) >= 3 {
+			count = len(values[1]) + 1
+		}
 	}
+	return strings.Repeat("`", count)
+}
 
-	planTemplate, err := template.New("plan").Funcs(funcMap).Parse(planTemplateBody)
+func (plan *PlanData) Render(w io.Writer) error {
+	planTemplate, err := template.New("plan").Parse(planTemplateBody)
 	if err != nil {
 		return fmt.Errorf("invalid template text: %w", err)
 	}

internal/terraform/plan_test.go

@@ -58,6 +58,7 @@ func Test_render(t *testing.T) {
 		{name: "all_types_mixed", wantErr: false},
 		{name: "aws_sample", wantErr: false},
 		{name: "iam_policy", wantErr: false},
+		{name: "include_code_fence", wantErr: false},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

test/testdata/include_code_fence/expected.md

@@ -0,0 +1,19 @@
+### 0 to add, 1 to change, 0 to destroy, 0 to replace.
+- change
+    - env_variable.test1
+<details><summary>Change details</summary>
+
+````diff
+# env_variable.test1 will be updated in-place
+@@ -7,7 +7,7 @@
+   ",
+   "name": "
+   ```
+-  test1
++  test2
+   ```
+
+   ",
+````
+
+</details>

test/testdata/include_code_fence/main.tf

@@ -0,0 +1,22 @@
+terraform {
+  required_providers {
+    env = {
+      source = "tchupp/env"
+      version = "0.0.2"
+    }
+  }
+}
+
+provider "env" {
+  # Configuration options
+}
+
+resource "env_variable" "test1" {
+  name = <<EOF
+
+```
+test2
+```
+
+EOF
+}

test/testdata/include_code_fence/show.json

@@ -0,0 +1 @@
+{"format_version":"1.0","terraform_version":"1.1.8","planned_values":{"root_module":{"resources":[{"address":"env_variable.test1","mode":"managed","type":"env_variable","name":"test1","provider_name":"registry.terraform.io/tchupp/env","schema_version":0,"values":{"id":"\n```\ntest1\n```\n\n","name":"\n```\ntest2\n```\n\n","value":""},"sensitive_values":{}}]}},"resource_changes":[{"address":"env_variable.test1","mode":"managed","type":"env_variable","name":"test1","provider_name":"registry.terraform.io/tchupp/env","change":{"actions":["update"],"before":{"id":"\n```\ntest1\n```\n\n","name":"\n```\ntest1\n```\n\n","value":""},"after":{"id":"\n```\ntest1\n```\n\n","name":"\n```\ntest2\n```\n\n","value":""},"after_unknown":{},"before_sensitive":{"value":true},"after_sensitive":{"value":true}}}],"prior_state":{"format_version":"1.0","terraform_version":"1.1.8","values":{"root_module":{"resources":[{"address":"env_variable.test1","mode":"managed","type":"env_variable","name":"test1","provider_name":"registry.terraform.io/tchupp/env","schema_version":0,"values":{"id":"\n```\ntest1\n```\n\n","name":"\n```\ntest1\n```\n\n","value":""},"sensitive_values":{}}]}}},"configuration":{"provider_config":{"env":{"name":"env","version_constraint":"0.0.2"}},"root_module":{"resources":[{"address":"env_variable.test1","mode":"managed","type":"env_variable","name":"test1","provider_config_key":"env","expressions":{"name":{"constant_value":"\n```\ntest2\n```\n\n"}},"schema_version":0}]}}}

test/testdata/include_code_fence/terraform.tfstate

@@ -0,0 +1,27 @@
+{
+  "version": 4,
+  "terraform_version": "1.1.8",
+  "serial": 1,
+  "lineage": "562fda8d-ad02-efe3-9568-b6dd139ef8f9",
+  "outputs": {},
+  "resources": [
+    {
+      "mode": "managed",
+      "type": "env_variable",
+      "name": "test1",
+      "provider": "provider[\"registry.terraform.io/tchupp/env\"]",
+      "instances": [
+        {
+          "schema_version": 0,
+          "attributes": {
+            "id": "\n```\ntest1\n```\n\n",
+            "name": "\n```\ntest1\n```\n\n",
+            "value": ""
+          },
+          "sensitive_attributes": [],
+          "private": "bnVsbA=="
+        }
+      ]
+    }
+  ]
+}