Add doc tests

Taken from the slint repo, these verify that the code snippets included in the docs compile.

Author: tronical

.github/workflows/ci.yaml

@@ -27,6 +27,20 @@ jobs:
       secrets:
           ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
           ANDROID_KEYSTORE_BASE64: ${{ secrets.ANDROID_KEYSTORE_BASE64 }}
+  tests:
+      env:
+          CARGO_PROFILE_RELEASE_OPT_LEVEL: s
+          CARGO_INCREMENTAL: false
+      runs-on: ubuntu-latest
+      steps:
+          - uses: actions/checkout@v4
+          - name: Install Rust
+            uses: dtolnay/rust-toolchain@stable
+          - uses: Swatinem/rust-cache@v2
+            with:
+                key: tests
+          - name: Build & run tests
+            run: cargo test
 
   deploy:
     runs-on: ubuntu-latest

Cargo.toml

@@ -2,8 +2,8 @@
 # SPDX-License-Identifier: MIT
 
 [workspace]
-members = ["crate", "examples/gallery"]
-default-members = ["crate", "examples/gallery"]
+members = ["crate", "examples/gallery", "tests/doctests"]
+default-members = ["crate", "examples/gallery", "tests/doctests"]
 resolver = "3"
 
 [workspace.package]

tests/doctests/Cargo.toml

@@ -0,0 +1,25 @@
+# Copyright © SixtyFPS GmbH <info@slint.dev>
+# SPDX-License-Identifier: MIT
+
+[package]
+name = "doctests"
+authors.workspace = true
+edition.workspace = true
+homepage.workspace = true
+license.workspace = true
+repository.workspace = true
+rust-version.workspace = true
+version.workspace = true
+publish = false
+build = "build.rs"
+
+[[bin]]
+path = "main.rs"
+name = "doctests"
+
+[build-dependencies]
+walkdir = "2"
+
+[dev-dependencies]
+slint-interpreter = { version = "1.12.0", features = ["display-diagnostics"] }
+spin_on = { version = "0.1" }

tests/doctests/build.rs

@@ -0,0 +1,101 @@
+// Copyright © SixtyFPS GmbH <info@slint.dev>
+// SPDX-License-Identifier: MIT
+
+use std::io::{BufWriter, Write};
+use std::path::Path;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let tests_file_path =
+        std::path::Path::new(&std::env::var_os("OUT_DIR").unwrap()).join("test_functions.rs");
+    let mut tests_file = BufWriter::new(std::fs::File::create(&tests_file_path)?);
+
+    let prefix = Path::new(env!("CARGO_MANIFEST_DIR"))
+        .join("../..")
+        .canonicalize()?;
+    for entry in walkdir::WalkDir::new(&prefix)
+        .follow_links(false)
+        .into_iter()
+        .filter_entry(|entry| entry.file_name() != "target")
+    {
+        let entry = entry?;
+        let path = entry.path();
+        if path.extension().is_none_or(|e| e != "md" && e != "mdx") {
+            continue;
+        }
+
+        let file = std::fs::read_to_string(path)?;
+        let file = file.replace('\r', ""); // Remove \r, because Windows.
+
+        const BEGIN_MARKER: &str = "\n```slint";
+        if !file.contains(BEGIN_MARKER) {
+            continue;
+        }
+
+        let stem = path
+            .strip_prefix(&prefix)?
+            .to_string_lossy()
+            .replace('-', "ˍ")
+            .replace(['/', '\\'], "Ⳇ")
+            .replace(['.'], "ᐧ")
+            .to_lowercase();
+
+        writeln!(tests_file, "\nmod {stem} {{")?;
+
+        let mut rest = file.as_str();
+        let mut line = 1;
+
+        while let Some(begin) = rest.find(BEGIN_MARKER) {
+            line += rest[..begin].bytes().filter(|&c| c == b'\n').count() + 1;
+            rest = rest[begin..].strip_prefix(BEGIN_MARKER).unwrap();
+
+            // Permit `slint,no-preview` and `slint,no-auto-preview` but skip `slint,ignore` and others.
+            rest = match rest.split_once('\n') {
+                Some((",ignore", _)) => continue,
+                Some((x, _)) if x.contains("no-test") => continue,
+                Some((_, rest)) => rest,
+                _ => continue,
+            };
+
+            let end = rest.find("\n```\n").ok_or_else(|| {
+                format!(
+                    "Could not find the end of a code snippet in {}",
+                    path.display()
+                )
+            })?;
+            let snippet = &rest[..end];
+
+            if snippet.starts_with("{{#include") {
+                // Skip non literal slint text
+                continue;
+            }
+
+            rest = &rest[end..];
+
+            write!(
+                tests_file,
+                r##"
+    #[test]
+    fn line_{}() {{
+        crate::do_test("{}", "{}").unwrap();
+    }}
+
+                "##,
+                line,
+                snippet.escape_default(),
+                path.to_string_lossy().escape_default()
+            )?;
+
+            line += snippet.bytes().filter(|&c| c == b'\n').count() + 1;
+        }
+        writeln!(tests_file, "}}")?;
+        println!("cargo:rerun-if-changed={}", path.display());
+    }
+
+    println!(
+        "cargo:rustc-env=TEST_FUNCTIONS={}",
+        tests_file_path.to_string_lossy()
+    );
+    println!("cargo:rustc-env=SLINT_ENABLE_EXPERIMENTAL_FEATURES=1");
+
+    Ok(())
+}

tests/doctests/main.rs

@@ -0,0 +1,53 @@
+// Copyright © SixtyFPS GmbH <info@slint.dev>
+// SPDX-License-Identifier: MIT
+
+#![allow(uncommon_codepoints)]
+
+#[cfg(test)]
+fn do_test(snippet: &str, path: &str) -> Result<(), Box<dyn std::error::Error>> {
+    let must_wrap = !snippet.contains("component ") && !snippet.contains("global ");
+
+    let code = if must_wrap {
+        format!(
+            "import {{
+                CheckBox, CheckState, Switch, TimePicker, NavigationBar}} from\"material.slint\";
+            component Example {{\n{snippet}\n}}"
+        )
+    } else {
+        snippet.into()
+    };
+
+    let mut compiler = slint_interpreter::Compiler::default();
+
+    compiler.set_include_paths(vec![std::path::PathBuf::from(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/../../"
+    ))]);
+
+    let result = spin_on::spin_on(compiler.build_from_source(code, path.into()));
+
+    let diagnostics = result
+        .diagnostics()
+        .filter(|d| {
+            let msg = d.message();
+            // It is ok if there is no components
+            msg != "No component found"
+                // Ignore warning about examples that don't inherit from Window or not exported
+                && !msg.contains(" doesn't inherit Window.")
+                && msg != "Component is implicitly marked for export. This is deprecated and it should be explicitly exported"
+
+        })
+        .collect::<Vec<_>>();
+    slint_interpreter::print_diagnostics(&diagnostics);
+
+    if result.has_errors() && !diagnostics.is_empty() {
+        return Err(format!("Error when loading {snippet:?} in {path:?}: {diagnostics:?}").into());
+    }
+    Ok(())
+}
+
+include!(env!("TEST_FUNCTIONS"));
+
+fn main() {
+    println!("Nothing to see here, please run me through cargo test :)");
+}