From 9ed32d57ef7e63c4d2d6fa21ca4f07d488e967da Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Wed, 14 Apr 2021 09:45:41 +0300
Subject: refactor: don't use anyhow in the library part of the crate

Add one variant to the SubplotError enum and change src/codegen.rs to
return Result<_, SubplotError> instead of anyhow::Result<_>.
---
 src/codegen.rs | 23 ++++++++++++-----------
 src/error.rs   |  6 +++++-
 2 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/codegen.rs b/src/codegen.rs
index 588fe1b..efb4081 100644
--- a/src/codegen.rs
+++ b/src/codegen.rs
@@ -9,10 +9,8 @@ use base64::encode;
 use serde::Serialize;
 use tera::{Context, Tera, Value};
 
-use anyhow::{Context as AnyhowContext, Result};
-
 /// Return the requested template specification.
-pub fn template_spec(doc: &Document) -> Result<TemplateSpec> {
+pub fn template_spec(doc: &Document) -> Result<TemplateSpec, SubplotError> {
     let template = doc
         .meta()
         .template_name()
@@ -22,7 +20,6 @@ pub fn template_spec(doc: &Document) -> Result<TemplateSpec> {
     filename.push("template");
     filename.push("template.yaml");
     TemplateSpec::from_file(&filename)
-        .with_context(|| format!("Failed to read template file: {}", filename.display()))
 }
 
 /// Generate a test program from a document, using a template spec.
@@ -30,14 +27,14 @@ pub fn generate_test_program(
     doc: &mut Document,
     spec: &TemplateSpec,
     filename: &Path,
-) -> Result<()> {
+) -> Result<(), SubplotError> {
     let context = context(doc)?;
     let code = tera(&spec)?.render("template", &context).expect("render");
     write(filename, &code)?;
     Ok(())
 }
 
-fn context(doc: &mut Document) -> Result<Context> {
+fn context(doc: &mut Document) -> Result<Context, SubplotError> {
     let mut context = Context::new();
     context.insert("scenarios", &doc.matched_scenarios()?);
     context.insert("files", doc.files());
@@ -46,7 +43,7 @@ fn context(doc: &mut Document) -> Result<Context> {
     let mut funcs = vec![];
     for filename in funcs_filenames {
         let content = resource::read_as_string(filename)
-            .map_err(|e| SubplotError::FunctionsFileNotFound(filename.into(), e.into()))?;
+            .map_err(|err| SubplotError::FunctionsFileNotFound(filename.into(), err))?;
         funcs.push(Func::new(filename, content));
     }
     context.insert("functions", &funcs);
@@ -54,7 +51,7 @@ fn context(doc: &mut Document) -> Result<Context> {
     Ok(context)
 }
 
-fn tera(tmplspec: &TemplateSpec) -> Result<Tera> {
+fn tera(tmplspec: &TemplateSpec) -> Result<Tera, SubplotError> {
     // Tera insists on a glob, but we want to load a specific template
     // only, so we use a glob that doesn't match anything.
     let mut tera = Tera::new(&"/..IGNORE-THIS../..SUBPLOT-TERA-NOT-EXIST../*").expect("new");
@@ -66,14 +63,18 @@ fn tera(tmplspec: &TemplateSpec) -> Result<Tera> {
         let helper_path = dirname.join(helper);
         let helper_content = resource::read_as_string(helper_path)?;
         let helper_name = helper.display().to_string();
-        tera.add_raw_template(&helper_name, &helper_content)?;
+        tera.add_raw_template(&helper_name, &helper_content)
+            .map_err(|err| SubplotError::TemplateError(helper_name.to_string(), err))?;
     }
     let template = resource::read_as_string(tmplspec.template_filename())?;
-    tera.add_raw_template("template", &template)?;
+    tera.add_raw_template("template", &template)
+        .map_err(|err| {
+            SubplotError::TemplateError(tmplspec.template_filename().display().to_string(), err)
+        })?;
     Ok(tera)
 }
 
-fn write(filename: &Path, content: &str) -> Result<()> {
+fn write(filename: &Path, content: &str) -> Result<(), SubplotError> {
     let mut f: File = File::create(filename)?;
     f.write_all(&content.as_bytes())?;
     Ok(())
diff --git a/src/error.rs b/src/error.rs
index 73cfbb6..eb70e28 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -12,7 +12,7 @@ pub enum SubplotError {
 
     /// Subplot could not find a file named as a functions file.
     #[error("functions file could not be found: {0}: {1}")]
-    FunctionsFileNotFound(PathBuf, anyhow::Error),
+    FunctionsFileNotFound(PathBuf, std::io::Error),
 
     /// The simple pattern specifies a kind that is unknown.
     #[error("simple pattern kind {0} is unknown")]
@@ -204,6 +204,10 @@ pub enum SubplotError {
     #[error("Couldn't find name of directory containing template spec: {0}")]
     NoTemplateSpecDirectory(PathBuf),
 
+    /// A code template has an error.
+    #[error("Couldn't load template {0}: {1}")]
+    TemplateError(String, tera::Error),
+
     /// Unknown classes in use in document
     #[error("Unknown classes found in the document: {0}")]
     UnknownClasses(String),
-- 
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