diff --git a/test/Makefile.am b/test/Makefile.am
index e510230..e4ff261 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -26,6 +26,11 @@
 check_PROGRAMS =
 TESTS = $(check_PROGRAMS)
 
+entitymap_json_unittest_SOURCES = entitymap_json_unittest.cpp
+entitymap_json_unittest_LDADD = $(top_builddir)/entity_map_json.o -lgmock
+
+check_PROGRAMS += entitymap_json_unittest
+
 # Build/add sample_unittest to test suite
 sample_unittest_CPPFLAGS = -Igtest $(GTEST_CPPFLAGS) $(AM_CPPFLAGS)
 sample_unittest_CXXFLAGS = $(PTHREAD_CFLAGS) $(CODE_COVERAGE_CXXFLAGS) \
diff --git a/test/entitymap_json_unittest.cpp b/test/entitymap_json_unittest.cpp
new file mode 100644
index 0000000..a380a9e
--- /dev/null
+++ b/test/entitymap_json_unittest.cpp
@@ -0,0 +1,223 @@
+#include "entity_map_json.hpp"
+
+#include <ipmid/types.hpp>
+#include <nlohmann/json.hpp>
+#include <utility>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+namespace ipmi
+{
+namespace sensor
+{
+
+namespace
+{
+using ::testing::IsEmpty;
+
+TEST(ValidateJson, FailWithNonArrayReturnsEmpty)
+{
+    /* The entity map input json is expected to be an array of objects. */
+    auto j = R"(
+        {
+            "id" : 1,
+            "containerEntityId" : 2,
+            "containerEntityInstance" : 3,
+            "isList" : false,
+            "isLinked" : false,
+            "entities" : [
+                {"id" : 1, "instance" : 2},
+                {"id" : 1, "instance" : 3},
+                {"id" : 1, "instance" : 4},
+                {"id" : 1, "instance" : 5}
+            ]
+        }
+    )"_json;
+
+    EXPECT_THAT(buildJsonEntityMap(j), IsEmpty());
+}
+
+TEST(ValidateJson, FailWithMissingFieldReturnsEmpty)
+{
+    /* There are many required fields, let's just validate that if one is
+     * missing, it returns the empty map.
+     */
+    auto j = R"(
+        [
+            {
+                "id" : 1,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 2},
+                    {"id" : 1, "instance" : 3},
+                    {"id" : 1, "instance" : 4},
+                    {"id" : 1, "instance" : 5}
+                ]
+            }
+        ]
+    )"_json;
+
+    EXPECT_THAT(buildJsonEntityMap(j), IsEmpty());
+}
+
+TEST(ValidateJson, AllValidEntryReturnsExpectedMap)
+{
+    /* Boring test where we provide completely valid information and expect the
+     * resulting map contains that information.
+     */
+    auto j = R"(
+        [
+            {
+                "id" : 1,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "isLinked" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 2},
+                    {"id" : 1, "instance" : 3},
+                    {"id" : 1, "instance" : 4},
+                    {"id" : 1, "instance" : 5}
+                ]
+            }
+        ]
+    )"_json;
+
+    auto map = buildJsonEntityMap(j);
+    EXPECT_FALSE(map.find(1) == map.end());
+    auto entry = map.find(1);
+    EXPECT_EQ(entry->first, 1);
+
+    /* TODO: someone could write an equality operator for this object. */
+    EXPECT_EQ(entry->second.containerEntityId, 2);
+    EXPECT_EQ(entry->second.containerEntityInstance, 3);
+    EXPECT_FALSE(entry->second.isList);
+    EXPECT_FALSE(entry->second.isLinked);
+    ContainedEntitiesArray expected = {
+        std::make_pair(1, 2), std::make_pair(1, 3), std::make_pair(1, 4),
+        std::make_pair(1, 5)};
+    EXPECT_EQ(entry->second.containedEntities, expected);
+}
+
+TEST(ValidateJson, EntryHasInsufficientContainerEntryCountReturnsEmpty)
+{
+    /* The container must have four pairs. (I don't know why, and maybe this
+     * restriction will change).
+     */
+    auto j = R"(
+        [
+            {
+                "id" : 1,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "isLinked" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 2},
+                    {"id" : 1, "instance" : 3},
+                    {"id" : 1, "instance" : 4}
+                ]
+            }
+        ]
+    )"_json;
+
+    EXPECT_THAT(buildJsonEntityMap(j), IsEmpty());
+}
+
+TEST(ValidateJson, ThereAreTwoEntriesOneInvalidReturnsEmpty)
+{
+    /* If any entry in the file is corrupt, the file is disregarded. */
+    auto j = R"(
+        [
+            {
+                "id" : 1,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "isLinked" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 2},
+                    {"id" : 1, "instance" : 3},
+                    {"id" : 1, "instance" : 4},
+                    {"id" : 1, "instance" : 5}
+                ]
+            },
+            {
+                "id" : 2,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "isLinked" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 2},
+                    {"id" : 1, "instance" : 3},
+                    {"id" : 1, "instance" : 4}
+                ]
+            }
+        ]
+    )"_json;
+
+    EXPECT_THAT(buildJsonEntityMap(j), IsEmpty());
+}
+
+TEST(ValidateJson, ThereAreTwoEntriesBothValidReturnsBoth)
+{
+    /* The map supports more than one entry, just validate this. */
+    auto j = R"(
+        [
+            {
+                "id" : 1,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "isLinked" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 2},
+                    {"id" : 1, "instance" : 3},
+                    {"id" : 1, "instance" : 4},
+                    {"id" : 1, "instance" : 5}
+                ]
+            },
+            {
+                "id" : 2,
+                "containerEntityId" : 2,
+                "containerEntityInstance" : 3,
+                "isList" : false,
+                "isLinked" : false,
+                "entities" : [
+                    {"id" : 1, "instance" : 6},
+                    {"id" : 1, "instance" : 7},
+                    {"id" : 1, "instance" : 8},
+                    {"id" : 1, "instance" : 9}
+                ]
+            }
+        ]
+    )"_json;
+
+    auto map = buildJsonEntityMap(j);
+    EXPECT_FALSE(map.find(1) == map.end());
+    EXPECT_FALSE(map.find(2) == map.end());
+
+    auto entry = map.find(1);
+    EXPECT_EQ(entry->first, 1);
+    EXPECT_EQ(entry->second.containerEntityId, 2);
+    EXPECT_EQ(entry->second.containerEntityInstance, 3);
+    EXPECT_FALSE(entry->second.isList);
+    EXPECT_FALSE(entry->second.isLinked);
+    ContainedEntitiesArray expected = {
+        std::make_pair(1, 2), std::make_pair(1, 3), std::make_pair(1, 4),
+        std::make_pair(1, 5)};
+    EXPECT_EQ(entry->second.containedEntities, expected);
+
+    entry = map.find(2);
+    expected = {std::make_pair(1, 6), std::make_pair(1, 7),
+                std::make_pair(1, 8), std::make_pair(1, 9)};
+    EXPECT_EQ(entry->second.containedEntities, expected);
+}
+
+} // namespace
+} // namespace sensor
+} // namespace ipmi