Refactor quickstart command and add quickstress command

bench

@@ -19,8 +19,70 @@ init_bench_handling();
 # NOTE: The quickstart command is first here so it will appear first
 #       in the help text and hopefully catch the user's eye
 
-#| Setup, build, and test default compilers
+#| Setup, build, benchmark, and compare default compilers
 multi MAIN ('quickstart', Str :$stop-after = '') {
+    my sub checkouts() {
+        my @compilers = < perl5 nqp-moar rakudo-moar >;
+        my @extras = < nqp-moar/master rakudo-moar/nom >;
+        my sub good-tag($tag) {
+               $tag ~~ /^ \d**4\.\d**2 $/ && $tag ge '2014.01'
+            || $tag ~~ /^ 'v5.'(\d+)\.(\d+) $/ && +$0 >= 18 && +$0 %% 2
+        }
+
+        guess-checkouts(:@compilers, :@extras, :&good-tag);
+    }
+
+    my @checkouts = quickprep(:$stop-after, :&checkouts);
+    return unless @checkouts;
+
+    say "\nRUN BENCHMARKS";
+    MAIN('time',    @checkouts);
+    return if $stop-after eq 'time';
+
+    say "\nPERFORMANCE HISTORY";
+    MAIN('history', @checkouts);
+}
+
+#| Setup, build, stress test, and diagnose default compilers
+multi MAIN ('quickstress', Str :$stop-after = '') {
+    my sub checkouts() {
+        my @compilers = < rakudo-moar rakudo-jvm >;
+        my @extras = < rakudo-moar/nom rakudo-jvm/nom >;
+        my sub good-tag($tag) {
+            $tag ~~ /^ \d**4\.\d**2 $/ && $tag ge '2014.01'
+        }
+
+        guess-checkouts(:@compilers, :@extras, :&good-tag);
+    }
+
+    my @checkouts = quickprep(:$stop-after, :&checkouts);
+    return unless @checkouts;
+
+    say "\nRUN STRESS TESTS";
+    MAIN('stress',   @checkouts);
+    return if $stop-after eq 'stress';
+
+    say "\nDIAGNOSE FAILURES";
+    MAIN('diagnose', @checkouts);
+}
+
+#| Figure out which tags to build and test by default
+sub guess-checkouts(:@compilers, :@extras, :&good-tag) {
+    my %tags := known-tags(@compilers);
+
+    my %default;
+    %default{$_} = %tags{$_}.grep(&good-tag) for @compilers;
+
+    sort gather {
+        for %default.kv -> $compiler, @defaults {
+            take "$compiler/$_" for @defaults;
+        }
+        .take for @extras;
+    }
+}
+
+#| Setup and build compilers
+sub quickprep(Str :$stop-after, :&checkouts) {
     say "CONFIGURATION";
     MAIN('config');
     return if $stop-after eq 'config';
@@ -33,29 +95,11 @@ multi MAIN ('quickstart', Str :$stop-after = '') {
     MAIN('fetch');
     return if $stop-after eq 'fetch';
 
-    # Figure out which tags to build and test by default
-    my @compilers = < perl5 nqp-moar rakudo-moar >;
-    my %tags     := known-tags(@compilers);
-
-    my sub modern-release($tag) {
-           $tag ~~ /^ \d**4\.\d**2 $/ && $tag ge '2014.01'
-        || $tag ~~ /^ 'v5.'(\d+)\.(\d+) $/ && +$0 >= 18 && +$0 %% 2
-    }
-    my %default;
-    %default{$_} = %tags{$_}.grep(&modern-release) for @compilers;
-
-    %default<nqp-moar>.push: 'master';
-    %default<rakudo-moar>.push: 'nom';
-
-    my @checkouts = gather for %default.kv -> $compiler, @defaults {
-        take "$compiler/$_" for @defaults;
-    }
-
     say "\nPLANNED CHECKOUTS";
+    my @checkouts = checkouts();
     .say for @checkouts;
     return if $stop-after eq 'plan';
 
-    # Extract, build, time, and compare the default checkouts
     say "\nEXTRACT CHECKOUTS";
     MAIN('extract', @checkouts);
     return if $stop-after eq 'extract'|'checkout';
@@ -64,12 +108,7 @@ multi MAIN ('quickstart', Str :$stop-after = '') {
     MAIN('build',   @checkouts);
     return if $stop-after eq 'build';
 
-    say "\nRUN BENCHMARKS";
-    MAIN('time',    @checkouts);
-    return if $stop-after eq 'time';
-
-    say "\nPERFORMANCE HISTORY";
-    MAIN('history', @checkouts);
+    return @checkouts;
 }
 
 #| Show benchmark configuration