update build.zig to be mostly stock

build.zig

@@ -1,13 +1,50 @@
-const builtin = @import("builtin");
 const std = @import("std");
 
-pub fn build(b: *std.build.Builder) !void {
-    // Standard release options allow the person running `zig build` to select
-    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
-    // const mode = b.standardReleaseOptions();
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) !void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
     const target = b.standardTargetOptions(.{});
+
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
     const optimize = b.standardOptimizeOption(.{});
 
+    const lib = b.addStaticLibrary(.{
+        .name = "lambda-zig",
+        // In this case the main source file is merely a path, however, in more
+        // complicated build scripts, this could be a generated file.
+        .root_source_file = .{ .path = "src/lambda.zig" },
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the library to be installed into the standard
+    // location when the user invokes the "install" step (the default step when
+    // running `zig build`).
+    b.installArtifact(lib);
+
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const main_tests = b.addTest(.{
+        .root_source_file = .{ .path = "src/lambda.zig" },
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_main_tests = b.addRunArtifact(main_tests);
+
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build test`
+    // This will evaluate the `test` step rather than the default, which is "install".
+    const test_step = b.step("test", "Run library tests");
+    test_step.dependOn(&run_main_tests.step);
+
     var exe = b.addExecutable(.{
         .name = "custom",
         .root_source_file = .{ .path = "src/sample-main.zig" },
@@ -16,12 +53,7 @@ pub fn build(b: *std.build.Builder) !void {
     });
 
     b.installArtifact(exe);
-
     try lambdaBuildOptions(b, exe);
-
-    // TODO: We can cross-compile of course, but stripping and zip commands
-    // may vary
-    // TODO: Add test
 }
 
 /// lambdaBuildOptions will add three build options to the build (if compiling