Refactors and improvements (#2)

* Make better use of the build system lazy paths.
* General re-organization.
* Get rid of pointless ConfigHeader.
* Use addCMacro to enable `ZSTD_MULTITHREAD` - and also the
  static-linking-only API.
* Make tests.zig import the bindings as a module

Author: InKryption

build.zig

@@ -1,33 +1,27 @@
 const std = @import("std");
 
-const package_name = "zstd";
-const package_path = "src/lib.zig";
-
 pub fn build(b: *std.Build) void {
     const optimize = b.standardOptimizeOption(.{});
     const target = b.standardTargetOptions(.{});
 
+    const test_step = b.step("test", "Run library tests");
+
     const zstd_dep = b.dependency("zstd", .{});
 
     const zstd_lib = b.addStaticLibrary(.{
-        .name = package_name,
+        .name = "zstd",
         .target = target,
         .optimize = optimize,
     });
+    b.installArtifact(zstd_lib);
     zstd_lib.linkLibC();
     zstd_lib.addIncludePath(zstd_dep.path("lib"));
     zstd_lib.installHeader(zstd_dep.path("lib/zstd.h"), "zstd.h");
     zstd_lib.installHeader(zstd_dep.path("lib/zstd_errors.h"), "zstd_errors.h");
 
-    const config_header = b.addConfigHeader(
-        .{ .style = .blank },
-        .{
-            .ZSTD_CONFIG_H = {},
-            .ZSTD_MULTITHREAD_SUPPORT_DEFAULT = null,
-            .ZSTD_LEGACY_SUPPORT = null,
-        },
-    );
-    zstd_lib.addConfigHeader(config_header);
+    zstd_lib.root_module.addCMacro("ZSTD_MULTITHREAD", "");
+    zstd_lib.root_module.addCMacro("ZSTD_STATIC_LINKING_ONLY", "");
+
     zstd_lib.addCSourceFiles(.{
         .root = zstd_dep.path("lib"),
         .files = &.{
@@ -61,24 +55,19 @@ pub fn build(b: *std.Build) void {
         },
     });
     zstd_lib.addAssemblyFile(zstd_dep.path("lib/decompress/huf_decompress_amd64.S"));
-    b.installArtifact(zstd_lib);
 
-    const module = b.addModule(package_name, .{
-        .root_source_file = b.path(package_path),
-        .imports = &.{},
+    const zstd_mod = b.addModule("zstd", .{
+        .root_source_file = b.path("src/lib.zig"),
     });
-    module.linkLibrary(zstd_lib);
+    zstd_mod.linkLibrary(zstd_lib);
 
-    // tests
-    const tests = b.addTest(.{
+    const tests_exe = b.addTest(.{
         .target = target,
         .optimize = optimize,
         .root_source_file = b.path("src/tests.zig"),
     });
-    tests.linkLibrary(zstd_lib);
+    tests_exe.root_module.addImport("zstd", zstd_mod);
 
-    const run_tests = b.addRunArtifact(tests);
-    const test_step = b.step("test", "Run library tests");
-    test_step.dependOn(&zstd_lib.step);
-    test_step.dependOn(&run_tests.step);
+    const tests_exe_run = b.addRunArtifact(tests_exe);
+    test_step.dependOn(&tests_exe_run.step);
 }

src/tests.zig

@@ -1,12 +1,13 @@
 const std = @import("std");
-const lib = @import("lib.zig");
+const zstd = @import("zstd");
 
-test {
-    std.testing.log_level = std.log.Level.err;
-    std.testing.refAllDecls(lib);
+comptime {
+    std.testing.refAllDecls(zstd);
 }
 
 test "writing & reading" {
+    std.testing.log_level = std.log.Level.err;
+
     const test_data = blk: {
         var bytes: [32]u8 = undefined;
         @memset(&bytes, 0);
@@ -20,18 +21,18 @@ test "writing & reading" {
     var compressed_data = std.ArrayList(u8).init(std.testing.allocator);
     defer compressed_data.deinit();
 
-    const compressor = try lib.Compressor.init(.{});
+    const compressor = try zstd.Compressor.init(.{});
     defer compressor.deinit();
     var buffer: [128]u8 = undefined;
-    const writer_ctx = lib.writerCtx(compressed_data.writer(), &compressor, &buffer);
+    const writer_ctx = zstd.writerCtx(compressed_data.writer(), &compressor, &buffer);
     const writer = writer_ctx.writer();
 
     try writer.writeAll(&test_data);
     try writer_ctx.finish();
 
     try std.testing.expect(compressed_data.items.len <= test_data.len);
 
-    var reader_state = try lib.Reader.init(compressed_data.items);
+    var reader_state = try zstd.Reader.init(compressed_data.items);
     defer reader_state.deinit();
     const reader = reader_state.reader();