feat: add support for argument to dfx build (#158)

Before it was completely ignored.

Fixes SDK-544

dfx/src/commands/build.rs

@@ -1,6 +1,7 @@
 use crate::config::dfinity::{Config, Profile};
 use crate::lib::canister_info::CanisterInfo;
 use crate::lib::env::{BinaryResolverEnv, ProjectConfigEnv};
+use crate::lib::error::DfxError::BuildError;
 use crate::lib::error::{BuildErrorKind, DfxError, DfxResult};
 use crate::lib::message::UserMessage;
 use clap::{App, Arg, ArgMatches, SubCommand};
@@ -106,7 +107,11 @@ fn build_file<T>(env: &T, config: &Config, name: &str) -> DfxResult
 where
     T: BinaryResolverEnv,
 {
-    let canister_info = CanisterInfo::load(config, name)?;
+    let canister_info = CanisterInfo::load(config, name).map_err(|_| {
+        BuildError(BuildErrorKind::CanisterNameIsNotInConfigError(
+            name.to_owned(),
+        ))
+    })?;
     let config = config.get_config();
     let profile = config.profile.clone();
     let input_path = canister_info.get_main_path();
@@ -162,7 +167,7 @@ where
     Ok(())
 }
 
-pub fn exec<T>(env: &T, _args: &ArgMatches<'_>) -> DfxResult
+pub fn exec<T>(env: &T, args: &ArgMatches<'_>) -> DfxResult
 where
     T: BinaryResolverEnv + ProjectConfigEnv,
 {
@@ -171,7 +176,11 @@ where
         .get_config()
         .ok_or(DfxError::CommandMustBeRunInAProject)?;
 
-    if let Some(canisters) = &config.get_config().canisters {
+    // Get the canister name (if any).
+    if let Some(canister_name) = args.value_of("canister") {
+        println!("Building {}...", canister_name);
+        build_file(env, &config, &canister_name)?;
+    } else if let Some(canisters) = &config.get_config().canisters {
         for k in canisters.keys() {
             println!("Building {}...", k);
             build_file(env, &config, &k)?;

dfx/src/lib/error/build.rs

@@ -17,6 +17,9 @@ pub enum BuildErrorKind {
 
     /// An error happened while compiling WAT to WASM.
     WatCompileError(wabt::Error),
+
+    /// Could not find the canister to build in the config.
+    CanisterNameIsNotInConfigError(String),
 }
 
 impl fmt::Display for BuildErrorKind {
@@ -39,6 +42,10 @@ impl fmt::Display for BuildErrorKind {
             WatCompileError(e) => {
                 f.write_fmt(format_args!("Error while compiling WAT to WASM: {}", e))
             }
+            CanisterNameIsNotInConfigError(name) => f.write_fmt(format_args!(
+                r#"Could not find the canister named "{}" in the dfx.json configuration."#,
+                name,
+            )),
         }
     }
 }

e2e/build.bash

@@ -32,3 +32,11 @@ teardown() {
     assert_command dfx build
     [[ -f canisters/hello/_canister.id ]]
 }
+
+@test "build can take a single argument" {
+    assert_command dfx build hello
+    assert_match "Building hello..."
+
+    assert_command_fail dfx build unknown_canister
+    assert_match "Could not find.*unknown_canister.*"
+}

e2e/utils/assertions.bash

@@ -64,7 +64,7 @@ assert_match() {
     else
         text="$2"
     fi
-    [[ "$text" =~ "$regex" ]] || \
+    [[ "$text" =~ $regex ]] || \
         (batslib_print_kv_single_or_multi 10 "regex" "$regex" "actual" "$text" \
          | batslib_decorate "output does not match" \
          | fail)