libexpr/print: do not show elided nested items when there are none

When the configured maximum depth has been reached, attribute sets and lists
are printed with ellipsis to indicate the elision of nested items. Previously,
this happened even in case the structure being printed is empty, so that such
items do not in fact exist. This is confusing, so stop doing it.

Change-Id: I0016970dad3e42625e085dc896e6f476b21226c9

1 files changed, 13 insertions, 4 deletions

diff --git a/tests/unit/libexpr/value/print.cc b/tests/unit/libexpr/value/print.cc
index 1f99b562d..ddf8b8b99 100644
--- a/tests/unit/libexpr/value/print.cc
+++ b/tests/unit/libexpr/value/print.cc
@@ -193,6 +193,9 @@ TEST_F(ValuePrintingTests, vBlackhole)
 
 TEST_F(ValuePrintingTests, depthAttrs)
 {
+    Value vZero;
+    vZero.mkInt(0);
+
     Value vOne;
     vOne.mkInt(1);
 
@@ -203,10 +206,16 @@ TEST_F(ValuePrintingTests, depthAttrs)
     Value vAttrsEmpty;
     vAttrsEmpty.mkAttrs(builderEmpty.finish());
 
+    BindingsBuilder builderNested(state, state.allocBindings(1));
+    builderNested.insert(state.symbols.create("zero"), &vZero);
+    Value vAttrsNested;
+    vAttrsNested.mkAttrs(builderNested.finish());
+
     BindingsBuilder builder(state, state.allocBindings(10));
     builder.insert(state.symbols.create("one"), &vOne);
     builder.insert(state.symbols.create("two"), &vTwo);
-    builder.insert(state.symbols.create("nested"), &vAttrsEmpty);
+    builder.insert(state.symbols.create("empty"), &vAttrsEmpty);
+    builder.insert(state.symbols.create("nested"), &vAttrsNested);
 
     Value vAttrs;
     vAttrs.mkAttrs(builder.finish());
@@ -220,9 +229,9 @@ TEST_F(ValuePrintingTests, depthAttrs)
     vNested.mkAttrs(builder2.finish());
 
     test(vNested, "{ nested = { ... }; one = 1; two = 2; }", PrintOptions { .maxDepth = 1 });
-    test(vNested, "{ nested = { nested = { ... }; one = 1; two = 2; }; one = 1; two = 2; }", PrintOptions { .maxDepth = 2 });
-    test(vNested, "{ nested = { nested = { }; one = 1; two = 2; }; one = 1; two = 2; }", PrintOptions { .maxDepth = 3 });
-    test(vNested, "{ nested = { nested = { }; one = 1; two = 2; }; one = 1; two = 2; }", PrintOptions { .maxDepth = 4 });
+    test(vNested, "{ nested = { empty = { }; nested = { ... }; one = 1; two = 2; }; one = 1; two = 2; }", PrintOptions { .maxDepth = 2 });
+    test(vNested, "{ nested = { empty = { }; nested = { zero = 0; }; one = 1; two = 2; }; one = 1; two = 2; }", PrintOptions { .maxDepth = 3 });
+    test(vNested, "{ nested = { empty = { }; nested = { zero = 0; }; one = 1; two = 2; }; one = 1; two = 2; }", PrintOptions { .maxDepth = 4 });
 }
 
 TEST_F(ValuePrintingTests, depthList)