Index execution tests

spec/ast/index_spec.rb

@@ -0,0 +1,88 @@
+RSpec.describe AST::Index do
+  it 'evaluates array index' do
+    expect(
+      AST::Index.new(
+        AST::Array.new([
+          AST::Number.new(1.0),
+          AST::Number.new(2.0),
+          AST::Number.new(3.0),
+        ]),
+        AST::Number.new(2.0)
+      ).execute(Environment.new)
+    ).to eq(3.0)
+  end
+
+  it 'evaluates hash index' do
+    expect(
+      AST::Index.new(
+        AST::Hash.new(
+          :a => AST::Number.new(1.0),
+          :b => AST::Number.new(2.0),
+          :c => AST::Number.new(3.0),
+        ),
+        AST::Atom.new(:b)
+      ).execute(Environment.new)
+    ).to eq(2.0)
+  end
+
+  it 'raises for out of bounds array index' do
+    expect {
+      AST::Index.new(
+        AST::Array.new([
+          AST::Number.new(1.0),
+          AST::Number.new(2.0),
+          AST::Number.new(3.0),
+        ]),
+        AST::Number.new(3.0)
+      ).execute(Environment.new)
+    }.to raise_error("Array index out of bounds")
+  end
+
+  it 'raises for non-integral key on array' do
+    expect {
+      AST::Index.new(
+        AST::Array.new([
+          AST::Number.new(1.0),
+          AST::Number.new(2.0),
+          AST::Number.new(3.0),
+        ]),
+        AST::Number.new(1.5)
+      ).execute(Environment.new)
+    }.to raise_error("Array index requires integer key")
+
+    expect {
+      AST::Index.new(
+        AST::Array.new([
+          AST::Number.new(1.0),
+          AST::Number.new(2.0),
+          AST::Number.new(3.0),
+        ]),
+        AST::String.new("5")
+      ).execute(Environment.new)
+    }.to raise_error("Array index requires integer key")
+
+    expect {
+      AST::Index.new(
+        AST::Array.new([
+          AST::Number.new(1.0),
+          AST::Number.new(2.0),
+          AST::Number.new(3.0),
+        ]),
+        AST::Atom.new(:atom)
+      ).execute(Environment.new)
+    }.to raise_error("Array index requires integer key")
+  end
+
+  it 'raises for missing hash key' do
+    expect {
+      AST::Index.new(
+        AST::Hash.new({
+          :a => AST::Number.new(1.0),
+          :b => AST::Number.new(2.0),
+          :c => AST::Number.new(3.0),
+        }),
+        AST::Atom.new(:d)
+      ).execute(Environment.new)
+    }.to raise_error("Key d does not exist on object")
+  end
+end